A close friend of mine is going through something similar. She tells me the doctors suspect Chrohn's, but like you I think she is also aware that it could be cancer.
I know it's difficult at any age to be told you have a disease, but at least you are addressing this early and you will soon get a diagnosis. Some people suffer for years without ever getting diagnosed.
I think you should try to be open to whatever it could be. Do research, look up blogs and web videos about people who talk about the condition. Educating yourself really helps.