21 year old male off and on burning stomach pain in the upper left and right. seemingly caused by certain foods that are fatty or like chocolate, or soda. never had this problem before a couple months after i got covid last year?

Heartburn is typically burning sensation behind the breastbone/sternum after eating. Regurgitation is reflux of gastric contents along with acid. Caffeine and chocolate, as well as alcohol, and nicotine, and fatty foods, are known to decrease the pressure of the lower esophageal sphincter, which causes reflux and heartburn. This also varies with the amount of food, and position changes like laying

There is not enough detail here to know what is going on. Certainly Covid can cause some gastrointestinal symptoms, but it is not clear if it is actually involved or not. You should see your primary care doctor or a gastroenterologist for evaluation. Good luck.