That sucks. I suffer from panic attacks too but not so badly.
Medication does wonders though, I usually don't need to take medication for my panic attacks but when i'm flying or in a really bad state of mind my mom will sometimes let me have one of her Xanax and that does wonders for panic attacks. I've also taken regular antidepressants/antianxiety medications and those really helped too.
In the mean time just try to hang in there and tough it out. You should try going back to school and see what happens, you might not even have a panic attack, and if you do just leave.
Another thing that helps me when I feel myself getting panicky in school, is to just ask to use the bathroom, get a drink of cold water, take a short walk and some deep breaths.
Hopefully you and your doctor can get things sorted out.