I had a one night stand 4 nights ago. (stupid i know)

I have now come out in a spot below my vagina, kind of on the inside of my right buttocks cheek. it was red and quite big (about the size of a peanut). i tried to squeeze it and some fluid came out instead of puss. it is now scabby and sore, although this might be caused by the intense squeezing.

I have no other spots anywhere in my genital area. Do you think this could be herpes or just a normal spot?? please help.

The guy had no scabs or spots on his penis.