Why do i pee so much after ejaculation or the next day after. please help?

I wonder "pee so much" means the urinary output is very high or it only means increased frequency & how long you've had this sx. You symptom is peculiar, not common. If volume is high and you do not drink a lot of fluid then I will be interested in the urine concentration, i.e. how diluted the urine is. If increased frequency, then I want to know your prostate volume before/after the ejaculation.

It is unusual. It could be from local irritation of the bladder or the area. If it persists then you will have to be examined by a urologist for Diagnosis and treatment