It sounds like it might be gastritis--inflammation of the stomach, which, coincidentally, can be brought about by using NSAID's like ibuprofen. And the oxycodone doesn’t help either. I had the exact same symptoms because of the major stress after Xanax and Klonopin withdrawals. I was diagnosed by a gastroenterologist, a doctor who specializes in the stomach, colon, and liver. Best of luck.