About a month ago I had sex with my wife and afterwards I noticed a couple of sores at the tip of my penis (and the start of one on the shaft of my penis). I have never had this before and it's been a long time since I've been with another woman. When I showered it hurt a bit as it was an open wound. It almost looks like a rug burn as if there wasn't any lube. I had masturbated a few time prior to this time of having sex and am wondering if it was brought on by this. The sores healed, but left a bit of a red mark. After about a month we had sex again. This time we used lube, but it happened again. I'm more than a bit concerned so if anyone had any ideas they would be much appreciated! Thanks!