I have a stomach ache once a month at the same time for about a week

[firehawk1121]

I'm and 18 year old male. I'm not the healthiest person but definitely not the worst on the health scale. I had major major stomach pains about 4 months ago and had to go to the hospital. It was just terrible nausea. They thought it was some sort of infection so they gave me some antibiotics and sent me home. I was fine for about a month and then I had another week (around the same time in the month) of stomach pains, although these were minor compared to the previous ones. I have been having this stomach pain and nausea for the last three months from about the 16th to the 24th or something like that. I have heard about ulcers and stuff like that and they say you have a dull pain and that is kinda what I feel like. But im just not sure what it is. Anyone have an idea? thanks