I’m not quite sure if I understand exactly what is happening, but my guess is that your glans has an inflammation, causing it to swell too much for the foreskin (and also to be sensitive). Go see a doctor; inflammations and infections have various causes, and he can recommend the bets treatment if this is the case. Also, for general good penis health, use a quality penis nutrient cream (health professionals recommend Man1 Man Oil). Choose on with she abutter, which helps provide soothing relief.
It sounds as though your foreskin is stuck behind the head and won't go forward. If that is the case, then you have a condition called "paraphimosis."
Paraphimosis is the name of the condition of a retracted foreskin that is stuck behind the glans penis (head) of the penis and will not go forward. One can read about paraphimosis on the Internet.
If the foreskin is tight enough it can cut off blood circulation to the head and cause edema (swelling due to fluid accumulation). Paraphimosis should be promptly reduced when it occurs. Paraphimosis may be reduced by squeezing the head of the penis really hard to force the blood to leave the head. This will temporarily reduce the size of the head at which time the foreskin may be brought forward.
If attempts to reduce the paraphimosis are unsuccessful, then one should go to the emergency room of a nearby hospital. It is not necessary or advisable to be circumcised although some old-fashioned doctors are likely to recommend it.
You may want to stretch your foreskin to make it wider so that it does not get stuck again.