What is this recurring rash that leaves holes in my skin?

[es335]

I just returned from a followup visit to my dermatologist and I'm very frustrated. I have a recurring rash that starts with a few little holes in a straight line and turns into larger holes in my arm. It is very itchy and painful once they holes are larger. No matter what I said to the doctor, she kept telling me that the lines were of my own doing. She actually told me to cut my fingernails. When I told her the lines were not scratches she treated my like a child and went back to telling me to cover it so I wouldn't keep scratching it. GRRRRR!
I've gotten this rash multiple times over the past 2 years and I'd really like to hear something other than instructions to cut my finger nails.

Here is the picture:
https://www.screencast.com/t/u0pbZ1YWeinv