Possible infection between thigh and testicle

Hi
I noticed today that there is what looks like a small area with infection inside my right thigh (between thigh and testicle). There is some pain when I touched it and I used first aid alcohol on it, which caused some pain...and later I used something called Erythromycin Ointment on it, which caused pain also. I don't remember there being pain before I found the infection. I had also had small infection there at the same place recently (maybe last month or so).

My initially reaction was that it was some kind of STD like herpes...but after looking at some pics of herpes, my condition seems different (like no red bumps or anything, just rash infection).

also, I couldn't shower for like a week due to circumstances...could that be due to that? Should I be worried about STD? I am not very sexually active. Last time I was with a sex worker was half year ago and it was limited (no oral, very brief intercourse with condom, etc).