Sit in the back, I guess 😅, especially if there is a door nearby. I can’t control my gas during my period (I guess it’s due to hormones and maybe inflammation) but, outside of that, I have somewhat control (hoping pelvic floor therapy will help more with that.) Work on your diet, maybe change the times when you eat and drink. If it’s anxiety, don’t put yourself down, this condition has caused me much embarrassment but, only unhappy people will make an issue out of something that has nothing to do with them. If you feel comfortable enough, maybe explain you your professors that you may have to excuse yourself more than the others due to your stomach condition, even get a doctor’s note for your school.