I Had An Itch On My Scrotum Today And When

I had an itch on my scrotum today and when I scratched it, it felt like someone put a blow torch on them, I did not know what it was and after the burning settled I looked down at my scrotum and there was two red circles, one was larger and a little swelled, while the other one was just red. I am almost positive I do not have an STD, what could it be?