I'm so sorry to hear that. There is no fixed cure for it but there are medicines that can be given to improve symptoms like bloating, stomachache, etc. You will need to consult a gastroenterologist.
A nutritionist can guide you extremely well for the exact diet plan that can suit him and help him lead a better life. Avoid trigger foods, they vary between patients- it could be beef, spices, channa etc.
For further consultation, you can choose from our list of best Gastroenterologists in Lahore and seek in-person advice.