It's called Phimosis, where the foreskin does not retract all the way. The way to releave this without amputation of your foreskin is to manually induce tension to the skin. Little by little and after some time the foreskin will loosen up. This is the first treatment to under go. It is also best to obtain a steroid cream that helps releave the tension. It is said to be 90% effective. And with manual tension it is helpfully ensured.
Seeing a doctor is always a good idea, but a doctor, depending on his level of education and background, might say that you should get a circumcision instead of taking a more conservative route. Circumcision is a reasonable solution, but it can and does hurt through the healing process, even with anesthesia.
DONT hurt yourself while trying to apply tension. Please...