Stomach Aches

For the past couple weeks now I developed this weird stomach ache/pain. Its almost like a nauseous feeling but not wanting to throw up. Just a bleh feeling. It happens when I first wake up and after I eat throughout the day. I am a college student so i’m thinking it has to do with my diet. I do snack a lot and only walk which is my exercise. I have been on B.C. and this hasn’t occurred before. Anyone have an idea? I do get constipated a lot but never with a stomach ache. I am starting my period according to my pills on sunday. I am having bad bloating but not sure if it’s my pms symptoms or this stomach issue.