Just this week I noticed that there is this vein on the BACK of my foreskin which seems to be bruised and blood leaking out or something. I'm refraining from masturbation/sexual activity because of this. There is no pain or anything, however it looks like spider veins or some kind of veins where it's darkened and quite black--it freaked me out at first while I was in the shower cleaning myself then noticing this vein. I have made an appointment over the phone with my doctor, but the operators are quite useless. I tried to explain to them the problem without trying to disclose too much information because privacy is an issue. I just mentioned "painless groin area problem" and they constantly kept questioning me..

But anyways, it's this vein about maybe a couple cm that looks bruised and is very dark/red, and seems to be leaking out. Do you think this will clear up or is it a sign of something serious? There is no pain however. What is the cause of this? I've NEVER had anything like this happen so it is making me quite worried.

No big deal. I had this happen on my nose. They removed it with a couple of minutes of laser treatment, never to happen again. Your spider veins may disappear on their own. If not, there is the painless laser treatment. It is not a sign of anything serious.