This could be the result of multiple things you could be allergic to the lube used, or condoms or you could just have a friction rash due to insufficient lube, if you were very concerned talk to your doctor.
When you were intimate, was the guy rough during sex? There are many factors linked to a sore vagina. But it sounds like you could possibly have a UTI (urinary tract infection) which causes soreness and burning when you use the toliet. That could be treated with a simple check up from your doctor.
make sure you do not have herpes.