This is Dr. David
this redness irritation could be an early dermatitis skin inflammation or infection.
you need to stay away from sex and masturbation for a while.
you should wash the area with mild soap and warm water daily after pulling back the foreskin
you should use an antibiotic ointment on the area like neosporin twice a day and see if that helps.
if that doesn't get any better, you should see a doctor or urologist for stronger antibitoic creams and pills.