Talk to Gastroenterologist on Burning Sensation

Hi

Usually when i pee normally nothing happens but when i face night fall and then after the ejaculation i immediately go to bathroom to pee at that time during peeing i feel burning sensation while peeing out and it hurts alot.. but if i stay for like 15 mints after the night then go to pee then everything remains fine and no burning sensation i feel.

I have already done tests and reports say that i have no STIs or UTI or something similar.