I'm having some problems with my vagina! Please help!!!?

I'm 17 and me and my bf have sex regularly for about a month now. We have sex 4 or 5 times every time we have sex which is mainly on the weekend. Well this week my vagina has been itching/burning and has like little cuts on the outside around the opening. And I noticed the other day with a hand held mirror that the very opening of my vagina hole it has turned white. At first I thought it was just white discharge but its my skin. What is wrong with me? I've been putting vaseline down there hoping it would heal but nothing. It can't be an STD bc I just had blood tests done and they never said anything about any STD's and me and him had already been having sex. Also I've taken about 4 different antibiotics in this months. Maybe that's why. But please help cause this is driving me crazy!