I've had the same problem, which is now totally cured. It may take a few years, but you have to just keep stretching it every day. It's expected that the head will be hyper-sensitive; I cured this by retracting the forskin in the shower and letting the water pour over it. It's extremely unpleasant at first, but after a while the nerves will calm down. Also try retracting it at home and just walk around with pants on for a while. Again, very unpleasant, but ncessary to decensitize it. Also keep in mind that lubrication makes forskin considerably more easy to retract.

Good luck!