What Causes Rashes All Over The Face And Legs?

my brother was put on predisone a year and half ago due to a rash that started on his buttocks. the rash has spread to the legs and face he s been prescribed cortisoid creams off and on over the last year but gets temporary relief and it comes back worse than ever. He should never have been prescribed predisone as he has glaucoma and the rash is weepy and worse than ever spreading rapidly through his hair. he s been told its everything from ecema to psoriasis but were very concerned its much more serious as he has no energy his personality has changed and he s unable to work. he also has large bruising all over his body.