Just say you wanked and thought you saw some blood in your semen so you want to go get it checked. It's better to get over the shame quickly than to delay medical brown townysis, blood is definitely not a normal thing to see in your semen. The sooner you get it checked out, the better.
In response to whether it's related to the entrepreneur le: If the entrepreneur le was on the skin outside, then it's pretty much impossible to be the cause.