I’ve had this problem a lot, especially recently with classes starting back up. Whenever I’m feeling overly anxious I try to ground myself and take deep breaths. I’ll also try to distract myself with a task that will help take my mind off of things. Having a mental map of bathrooms nearby can help relieve some of that stress!

If you can figure out of you have trigger foods, I'm sure avoiding those would help. For the anxiety try describing (in your head or aloud, whichever works) everything you can see, hear, smell, touch, and taste in great detail. That's more of an anti- anxiety attack tactic than something for lingering worries but it still might help. I find it also helps to ask questions like "if I really do need to go in the middle of something, does it matter that much?" or "can I make sure others know I might need to leave suddenly for that reason?"