Can I sue my school or make a claim if I get an UTI because of my teachers?

I have to give you an "A" for creativity.  It is my understanding that Urinary Tract Infections are the second most common type of infection.  Respiratory is number one.  UTI's are self-limiting, in other words, they last a short period of time.  And, although there are antibiotics and antibacterials to help clear-up a UTI, sometimes, drinking a lot of water will help flush out the UTI. This being said, it is my opinion you don't have enough damages to justify a lawsuit.  It will cost more for the lawsuit than you can win. As a suggestion, let me suggest, you set-up a meeting with principal or assistance principal, your parents or guardian to see if you can change the school policy, where you are allowed to use the bathroom.  It would seem to me, that your teacher would be very uncomfortable to attend such a joint meeting.