Im 13 and i think i have a stomach ulcer?

im 13 a girl and i always have stoamch pain i would have it for a few minutes and then go away and then come back in a half an hour my parents think i could be a stoamch ulcer i have stoamch pain constant burping and farting i think it could be ibs or stomach ulcer or cancer how likley is it for a 13 year old to get stomach cancer o and if it is an ulcer can you drink beer or smoke weed whild you have it just wondering b/c my friend has a stoamch ulcer too please no rude comments just answer the questions