what is this scabby rash ive had on my arm for 10 months?

[jenpisces]

So this started when I started working at a dog bathing place. It started as a tiny little itchy spot which I thought was poison oak/ivy. Didn't pay much attention to it. Then it spread up and down my arm. Right along the nerve. I itched and scratched until it would pour blood then it would burn and hurt so bad i cry and cant move it. its caused my thumbnail to have indentions in it now..little tiny white pimples come up in it and thats what itches.. if i do end up giving in and itching they pop...then ooze.. after itching at all a clear puss seeps from my arm and it sweats and when it burns so bad. and it goes from the base of my thumb nail to right about before my elbo. I thought it was shingles.. ive been treated for that (i know there isn't a "cure") and i've tried steroids, salt water, vasaline, anti virals, herpes medication, not itching it pretty much everything i've been recommended to try.. ive done and NOTHING even touches it... and its STILL here. it doesn't look even slightly better.  I cant take it anymore!! Ive seen four different doctors who cant diagnose it. PLEASE help me!