I have similar problems when I'm stressed- really itchy down there, and sometimes my skin splits (looks a bit like mouth ulcers). I've been to the GP a couple of times, and apparently it's fairly common. I was given hydro-cortisone cream to try to get rid of it (didn't work very well- it did get rid of it for about a month, but it's come back :/) and nappy rash cream (awkward thing to get from a pharmacy aged 17... Anyway) to ease the itchiness.
If I were you I'd talk to a female GP (seriously, I talked to my male GP about it, and he looked like he felt very awkward, and didn't really help with anything, just established it wasn't an STI, which, being a virgin, I'd figured.) and discuss how to cope with it, as well as what it might be... I found it very comforting... Best of luck! x