Having symptoms of gastritis over last 2.5 weeks &have linked it to taking motrin. i've stopped & changed my diet. how long til it goes away?

Depends: It depends on the severity of the gastritis. Without medications like prilosec, bland diet, avoidance of caffeine, alcohol and stress it may take weeks to heal. If you're not feeling better by now see your physician or a gastroenterologist.

A lot faster with Rx: Unless there are other inciting risks to inflammation in your stomach (like h.Pylori, tobacco, too liberal alcohol, Aspirin or other nsaid's, etc.) your gastropathy will likely heal within a few days. Of course, you can speed up the healing process by starting an acid blocker drug like Prilosec otc daily.