Blister/Cut directly above anus. So scared!

I am deathly afraid that I have some STD. I'm 20 years old and I had sex with a stranger, stupidly. I am freaking out now that I have gotten some form of STD. It's a blister-like thing right above my anus, which started to develop a couple of days ago. It wasn't overbearingly painful at first, but as I got more nervous I popped it. Since then it's gotten moderately more discreet looking, but hurts and is uncomfortable if I sit on it, I can't directly see this mark but from what I've seen it looks even somewhat like a spider bite or a burn or a pimple, and it stings terribly when I put alcohol on it. I also thought it could be something that resulted from a hemorrhoid (because it has been uncomfortable to go to the bathroom as well). It has not bled, but has had some mucus discharge (very mildly, only when wiping/touching). I am so regretful and embarrassed that this has happened. I really need any bits of information and I'm even mortified to go to the doctor, let alone tell my parents. Please help me.

I doubt it would be an STD, unless you had anal intercourse. It sounds more like an external hemorrhoid, which when left alone normally goes away. Some cases are more severe and they don't go away and it can turn very bad. In your case, you popped it which was a pretty bad idea no matter what it is. Go see your Doctor and get a real opinion. The longer you leave it the worse it's going to get, and stop messing around with it.

There's nothing to be ashamed about when going to the doctor for something like this, even if it turns out to be an STD. It's completely confidential and no one else has to know about it. I find it odd that you would come to a site like this asking for advice from complete strangers on the internet rather than getting a real medical opinion from a doctor.

Now go get a real opinion from a real doctor before it gets worse and you regret not going sooner.