Re: penis foreskin problem
The most likely cause of your issue is phimosis. All it means is that the opening of the foreskin is too small to allow the skin to be pulled back. There are ways of stretching the opening without the need for surgery. If you look around, there is a whole section on this site about stretching the foreskin. Many people have recommended it.
To answer your other questions, you could have a problem with your frenulum too but it is probably not the cause unless you can see or feel that it is tight. Phimosis is not something that happens to every guy but it does happen. Age is really not a factor at this point. It will most likely not go away without you either stretching the skin or having a doctor treat it. Some guys have it treated, some leave it alone, and some do not even know they have a problem.
If you have any other questions, feel free to ask.
Good luck to you.