My mother had a rash starting about 3 months ago... it started of as a small rash than it keep spreading all overy her leg.than to other leg... she is constantly scratching and feels.the urge to scratch... I've took her to the hospital and doctor none of the prescription has helped at all... I don't know what to do

Sadly there really nothing anyone online can do. Only a doctor can help, and it seems that even that isn't working.

I would take her to a dermatologist, or have your family doctor recommend a specialist.

Good luck.