Dealing with Chronic Digestive Issues

My episodes are usually very similar: I start during the day with horrendous tasting/smelling burps that get increasingly worse. By evening my stomach starts hurting and also gets gradually worse. By midnight I'm in agony and start vomiting. Sometimes I get diarrhea in the middle of the night too. I usually get a couple hours of sleep and by morning the gas, pain, and vomiting have subsided. Today was different. While I'm not in agony like I was last night, my stomach pain hasn't gone away. I've eaten light meals and drank water, but I still have that gnawing stomach ache.