What Causes Burning Sensation Between The Buttocks?

Hi! Lately I ve had a bad burning feeling between my but cheeks pretty much by my anus. It looks like I have 2 blisters on one side of my anus and a smaller one one the other side. Also it feels like I have a cut between my vagina and anus. My vagina is not sore or itchy or bothering me at all it s mainly just between my butt cheeks. The pain is pretty uncomfortable and I would just like to see what you think it could be? Do you think I could have an std or just have an infection or something else down there? I also had a really bad uti not too long ago so could this maybe affect it? This also started the day after from the night I went out I had diarrhea the next day so that s what started to irritate it the next day. I haven t been wearing thongs so I don t irritate it anymore. I keep myself very clean. I will send a picture if you would like to see what it looks like so you can get a better look at what s going on.