What Causes Dry And Itchy Patches In Pubic Area?

When I was pregnant I used to get an itchy red rash in my bikini line. I wrote it off to skin irritation due to sensitivity.

Now, a year an a half later it has returned with a vengeance. I have discolored patches on both sides leading into my pubic hair. It itches and at stages becomes dry and flaky. I am terrified that I might have some form of venereal disease that I have never picked up ( I am very careful with these things and go for tests on a yearly basis) or that it might be psoriasis.