I've been diagnosed with acute gastitus, is it ok to exercise with this, such as bike or run? will exercise help alleviate this condition?

A broad diagnosis: Acute gastritis is usually an umbrella term for a bunch of issues involving the lining of the stomach (called the gastric mucosa). Normal exercise should be fine ... I always say to my patients, "the body is extremely smart - listen to it and stop if you feel discomfort, it usually gives you a warning sign if you're doing something wrong." Hope that helps!