How To Treat Stinging Pain And Itchiness In Vagina After Having Unsafe Sex?

I've recently been struggling with problems in the vaginal area, it started during sex when i noticed a stinging pain while the penis was being inserted but i thought nothing of it. It has now been 4 days after sexual intercourse and i am having very uncomfortable pains in my vagina, it is also itchy in and around the vagina, it is red, sore and burns. I have only slept with one person recently which was my boyfriend however on a break with my boyfriend i had sexual intercourse with another male. Both people was unprotected sex. I was wondering if you could tell or help me to what this may be as it is very painful before facing the embarrassment of going to my GP.
Thanks.