15 year old with possible colon cancer?

[SugarLoafs]

Since january this year I've been having really horrible pains/cramps in my stomach and lower intestine areas, which is always followed by diarrhea. It happens about twice a week now. The pain is really bad and has woken me up in the middle of the night several times to go to the bathroom. My dad always asks me whats wrong when this happens and i really don't know what to tell him. I only think it could be colon cancer because of the stomach pains and prolonged diarrhea, neither of which have been a problem for me before this year. Also my grandpa died from colon cancer if that means anything significant. I don't know if I'm having any "anal bleeding" or blood in my stools because i don't exactly look to check for it. But yeah this has been going on for months and I'm too embarrassed to say anything about it, I'm only about to turn 15 so id probably sound stupid to my parents for thinking i have colon cancer.