Welcome to YT!
Sorry your girl is having so many problems. I would go to the vet to see if you could get immediate help. Also, a bath in a good oatmeal shampoo & conditioner or something designed to treat itchy skin will help give some relief. This is a good choice - and an amazing price right now
HyLyt Shampoo (8 oz) and this rinse
Relief Creme Rinse - 8 oz
After the vet and the bath, I would look at her diet - she may be allergic to her food. What are you feeding her?
Make sure that food doesn't have corn in it - this is one of the biggest allergens -- but there are others too.