There are a couple of types of mange it could be. It could also be a flea allergy. I hope you get affordable help for her. She does not sound comfortable.
Please contact any local Humane Society or SPCA in your area....They will be able to direct you to a low income clinic if they don't provide one themselves......
If you could elaborate on her bloches & hair loss, we may can steer you in the right direction.....