I have recently had unprotected sex with my girlfriend, and a few days after the last time we had sex, I woke up with and found the left side of my penis head to be very sensitive to touch, such as even rubbing up against my underwear or to the touch of my finger. I have no other pain, no issues urinating, and nothing else seems to be wrong, but I'm worried at what it could be. It has been a few days and it is not as sensitive as it was when it first started but it is still there and I don't know what the issue could be, if there is an issue at all. Is this something I should be concerned about and should have checked out by a physician?