Suggest Treatment For Patch On Back Of Scalp

Hello, I am a 26 year old female. I have had a patch on the back of my scalp about the size of a small adult fist. When dry, it is extremely itchy (So bad that I have noticed I scratch at it in my sleep) it does not flake like dandruff. It's almost gritty. When my scalp is wet, if I scratch at it, I realize that it collects under my nails as a paste like consistency. This developed during my pregnancy and has not gone away. I have tried ciclopirox (sp?) and it has not resolved.