One of our kids went through panic attacks.  They were very real.  But they were also very limiting.  Resulting in a host of isolating behaviours.  It's a fine line between acknowledging them and enabling them.  For us we found that s/he would excuse themself from class when a panic attack was coming.  But it became more often.  And eventually started impacting other areas (as well as grades).  We were lucky enough to be able to get to the bottom of the cause of the attacks (bad situation s/he was exposed to when not with us) which was the key to it all.  But in the meantime, we had a very frank discussion that the goal was to cope with them, whether or not they continued.  So coping techniques we the first line of defense.  That meant that excusing oneself from class was one of the LAST techniques, and leaving school altogether for more than a period meant a whole lot more practice and chats with parents or counsellors.  

We put expectations on SK that s/he didn't have to be perfect, but should be progressing.  Mastering the techniques did not mean the panic attacks were fewer or lesser.  It meant the reactions to those attacks were more productive.  Like breathing slowly, or doodling in a book, reciting a mantra...whatever it took to get over the attack, and refocus on the normal life of a teenage. 

Good luck.  Talk to the counsellor to make sure your SD has the tools she needs, and then explain your expectations.  Leaving school is not a solution.  At best she can leave class and find a quiet place for a period of time.  And eventually you expect her to be able to manage these attacks without even leaving class.  (And see if you can figure out if there are any new root causes that should be eliminated such as a loud teacher, or a mean classmate).

My SS16 has those as well and has ruined outings and vacations for the family often. His mother coddles him and flies to his rescue to remove him from any environment he might deem anxiety inducing

SS16 has locked himself in bathrooms and cried during bday parties (for unknown reasons) and events involving fun activities. He cannot be dropped off anywhere with other teens because he is socially inept and will asked to be picked up immediately. He has 0 social skills and eventually dropped out of school at 16 to get in an accelarated graduation program (so they claim) after he had multiple panic attacks at school and made suicidial and homicidal threats. He frequently would leave school or miss school and blame it on anxiety and panic. He is now on Prozac and plans to work in a home improvement store and launch a career in music hahaha

These "types" actually have a tendency to be lazy and escaping responsibilities. You cant do anything about it. We flew SS16 out of state for his first vacation ever (he never went out of state or city to vacation except 3 days to the beach/year) and the whole time he refused to partake in activities and was rude/ignoring adults and stayed on his phone in his room

Strangely, he does not experience anxiety when it comes to being around his gf and her family and doing activities....

She will drop out eventually and use this excuse to not do what she doesnt like doing (like going to school, chores, having responsible social interactions, etc)

Take it from me. Sd needs to get a grip on her panic attacks now, or she will always be using them to get out of life. Get a job? Can't - it gives me panic attacks! Move out? Can't. It gives me panic attacks. Learn to drive? Can't. (You see the pattern here.) My SD is 19 and still uses her anxiety to hide from the world and avoid adult responsiblities. 

I've never met a human that scares the daylights out of themselves with an unexpected fart. Usually you only see that in cat videos. LOL.  But seriously. This kid needs a therapist that can see through her bullshit and help her figure out why she feels the need to lie and manipulate. 

I have experienced panic attacks for years, they are no joke and feel very real. There isn't always a logical reason for them and it sucks. That being said, they aren't an excuse to get out of life or responsibilities. My son also has them.

I would talk to her doctor about a daily medication to help ease this anxiety that she is having. There also would be nothing wrong with having her tested for IBS or Crohns. Maybe it is more than a little gas pain, maybe it's not. It could be manipulation or it could be real. Teenagers are REALLY HARD. 

Another thing that might help if she is having these panic attacks at school is getting her a 504 plan. My son is allowed to basically wave at his teacher and leave. Go to guidance and have his moment, breakdown, whatever and then head back to class. Just knowing that he doesn't have to break down in class has made it 100X better. He doesn't have to ask, he doesn't have to get a hall pass- just leave. He doesn't take advantage of it, but he will use it if he needs to. 

Have a great deal of experience with this , other than my niece 15. In short her mother's a hypochondriac and has led the child down the same path, there had to be something special about her, and so it's been engrained that (in her case) there must be something wrong. She had one incident as a child where she had her tonsils out, a bleed became an emergency. Since then she's allowed, and I do say allowed, to either panic or have meltdowns for anything and everything she does not want to do, or finds remotely difficult.  Has there ever been an incident such as this that would cause her to believe her panic /anxiety/mistrust is correct?

I should add that, niece has been seeing a therapist over her parents breakup and they phoned her dad directly to say they believe she's actually autistic.  That could be an area to research?

Otherwise , as others have said above , if its that bad she needs dr/medication to reduce the impact on all your daily lives 

I've had a panic attacks and I've also had Gallbladder issues. The symptoms can be quite similar. Lightheaded, difficult to breathe, chest pain, flushing, etc. Might be worth looking into - especially with the digestive issues. 

Also, if she has a therapist. She should have a plan for what to do in school & what to do when she is alone when she has a panic attack. Going home should not be an option. Quite frankly, if she can make a call during the panic attack; she's capable of working her way through it.