What Causes Brown Discharge After Urination?

i have been having brown discharge when i pee and when i finger to clean inside i get a ton of brown discharge but i have always had normal discharge i have never had a period i have never had spotting i have only had this i have never had period side effects and i do masterbate and watch porn but im a virgin and im overweight(like 240) and i am 13

i sleep from 4pm-12am(awake at night) and i am only eating 2 times a day and have no medical problems as far as i know(except a broken leg so i dont walk) and i might have a sleeping disorder