gee111, I am not a doctor, and suggest that you may want to seek one out, but I will say that potentiallly you may have lost some sensitivity on the skin of your penis (shaft and/or head). Loss of sensitivity would prolong the erection and stave of ejaculation (which is why some fellows buy cream specifically to dullen the exciting feeling they get so that they can prolong it).
It is important to have a healthy sex life, and to be able to masturbate if only to relieve stress, and so I would suggest you check in with your doctor.

Wendy

What you are experiencing is normal for circumcised guys. Circumcision does two things to the penis. First, it removes a significant portion of erogenous tissue that has lots of fine touch nerves. Second, it exposes the glans (the head of the penis) and any remaining inner foreskin to the air and to your clothes. This exposure, over time, desensitizes the circumcised penis. Initially, immediately after circumcision, the penis is very sensitive, but after a few months, it gets less sensitive. Many men, including those who have been circumcised as adults, have restored their foreskin to regain some sensitivity.