I think your best bet is to make an appointment with your doctor. It could be lots of things and cancer is far from the most likely, especially if you are under 60. But whatever it is, it's best to get it checked out. It's quite likely to be something quite minor and you will be reassured. And if it is something more serious, like Crohn's or whatever, the sooner you get it checked out, the sooner it's dealt with. Hope you get good news.