What Causes Grey Patching And Itching All Over The Body?

I am 37 yr old female have skin problem of patches of gray over the legs and severe itching all over the body since more than a year. Few months back i have consulted a lady doctor in chennai who has prescribed me Momate F cream, Alsuth lotion, LS dew soap, T.Azifast, T.Zeneoma, T.Altegra, T.Lorday. But the problem is solved temporarily and again there is severe itching. Tell me the solution and the best lady skin doctor in chennai