I'm a little confused - are you getting stretching of your foreskin done professionally, like by a doctor?
It's possible the stretching is desensitizing things a bit, and this is temporary. It may just be that you don't achieve ejaculation from direct stimulation. That's okay - every person is different on what makes them achieve ejaculation. This doesn't mean there is something wrong with you.
Have you talked to your doctor about all of this? If you aren't having a professional do the stretching, PLEASE talk to your doctor about it.