If you're worried, go and see a doctor. Chances are, it's nothing, but it could be something, and the faster you find out the greater the likelihood that something can be done easily. Even if it is nothing (which is probably the case), having a doctor tell you that you're fine will mean that you won't be worrying about it, and any doctor worth their salt would prefer you to get checked out than see you in six months and have to tell you something life-changing.