Dry Psoriasis

My sister is suffering from psoriasis only at the edges of the feet ,there is blackish dark brown spots only at the edges of feet. .visited many doctors some said its psoriasis and others said its keratoderma. .when she put her feet in warm water more than 10 minutes. .sometimes little bit skin peels off..tried many salicylic contained creams n ointment and also steroid injections too..but didn't get any result. .Please help me how to get rid of it completely. .or it can be cure completely...?? Is homeopathic treatment can work for her to cure the disease? Should we try?? Please help me..It's humbe request