What is causing the itchy rash on my wrist?

I've had an itchy rash on my wrist for months now... my right wrist (about a quarter size and kinda on the left of my wrist) and I have no idea what's causing it. Nobody else in my house has had anything like this and so now I really have no idea of what it is, at ALL. I don't have any health insurance to go in and get it checked out either. It gets super, super itchy and then get's little bumps all over and they open up (I've got long nails & it feels good, ughh) and then it might not itch for a week or so and then a few days later. At night, in the morning, cold and hot weather..... Hmmmm, any ideas???