Hi guys I'm a 17 year old male in the UK and I have a bit of a problem with my penis foreskin. When my penis is flaccid the foreskin goes over my whole head and an additional centre metre and a half but when it's erect it covers about 5/8ths of the head. I can only just pull it past the head but it quite literally strangles the head and the head also goes red .the thing connecting the foreskin to the head of the penis goes white when pulled ,not even past the head and it is very painful. at the moment i am sexually active and sex is painful to say the least and I always have to cut it short because of this problem.

I am desperate for help at the moment and this is a really sensitive issue for me, so if you can give me some advice I would really appreciate it.
cheers guys