After Colonoscopy/endoscopy, My Son, 16 Years Old Was Diagnosed To

After colonoscopy/endoscopy, my son, 16 years old was diagnosed to have chronic colitis (ulcer 1, .2cm, ulcers 2 & 3, both .4 cm.), erosive gastritis, h. pylori and hiatus hernia. He has recurring fever for more than a month after he was diagnosed to have those diseases. His CBC platelet, WBC, RBC were all abnormal together with his ESR ranging up to 90. He was given omeprazole for 1 month, mesalazine (salofalk 500 mg/4x day), for almost 3 months now and taking azathioprine 50 mg/1xday for 11 days now. But i have observed he has recurring fever, bloatedness and stomach pain from time to time. How long is the treatment for these diseases, proper diet and possible adverse reactions of the medicines he is taking?