Hello, my 13 year old son weighs about 200 pounds, and is having clear anal discharge. please help?

See his doctor: Anal discharge needs to be evaluated to determine cause. A fistula, infection, inflammation (to name a few) could all lead to anal discharge and require different treatment. Depending on cause, his weight may or may not be contributing. Lifestyle modification - nutritious whole foods, avoiding processed foods, and exercise - will help his weight and start a life of healthy habits.