Well, a lot depends on what part of your thumb hurts, but I would suspect a possible sprain, in which case you need to have it taped with athletic tape. Does your school have an athletic trainer? If so, go to him/her and ask them for advice. If not, maybe your coach(es) may have an idea on how to treat this. A lot of times when schools don't have athletic trainers the coaches are pretty well informed about things like this, as they must watch out for the athletes' physical health. I would suggest a nurse as your third option. Hope I helped.