If it hurts on the right side, near your pelvic bone, it could be your appendix. (Hope it‘s the right word, english is not my first language) Try to jump (just up and down, once or twice). When you land and it hurts like period cramps, it could be your appendix. (If something‘s wrong with the appendix the landing hurts, like someone is poking you with needleor like period cramps... I‘m sorry, I can‘t really explain it in English....)
I didn‘t study medicine, what i said doesn‘t have to be true. Please, go see a GP!!!