Hi I'm 15 and when not erect I can easily roll my foreskin back over the head of my penis and even abit further however when erect I can just about pull it over the head. However this is not with ease when erect I have to slowly pull it back also when the foreskin sits behind the head of my penis I cannot then pull it any further back without it hurting which I do not experience when flaccid. Could someone please tell me what I can do to fix this?
It depends on why it won't go back. What is stopping it? Is your frenulum keeping it from going any further? If so you will have to get that cut to fix that problem. It's a simple operation and well worth it. It is such a pleasure to have that out of the way so your foreskin can go all the way back without any pain.
The other thing could be the tip being too tight. That can be stretched using your fingers. Just put two fingers in the end and pull them apart a bit to apply pressure for a few minutes every time you take a shower or as often as you feel like doing it. That will stretch the opening after a few weeks.