My son was circumcised when born, now has erection that bend upwards where the scar is on dorsal side. too much skin was removed? it is very tight.

I assume your son is: An infant or young child. Show your pediatrician. Rarely, foreskin is cut to the point that intercourse is painful for a male, which wouldn't be an issue prior to puberty. If you are really concerned, request referral to a pediatric urologist to determine if there is any anatomical malformation of the penis that would cause your son to have a medical problem.