question: Hi I have been having pain in my upper abdomen, it s a burning sensation. My doctor put me on a 40mg prilosec OTC over the counter meds for he thinks its an ulcer For two weeks. I recently won t to the dentist 5 days ago for a tooth infection and I was given penicillin . I ve been taking both prilosec and penicillin. I ve noticed I ve had stomach aches and have more bowel .movements about 3-5 a day. Right after eating. Is this from a the meds combo or maybe a possible ulcer? Thank you Oh by the way I am 24 years old 5 10 165 pounds also noticed I can t put on wieght and have been tiring. I may suffer from stress and anxitey