STD/STI? TMI picture

ok so my ex boyfriend cheated on me and i dont think he used a condom and well i didnt know about it and we dont use condoms as im on birth control and anyway i have these rash like spots and i didnt notice them until it got quite sore and a little itchy i havent been tested or anything and i will if this is similar to an std or sti i dont really know whats what exactly but yea there is no point worring if its just a rash from a thong or shaving or something