Terrible rash

Patient: My 55 yr. old son who has had a stoke in the past has this terrible rash on this skin and from head to foot he turned a bright red. His doctor says he is allergic to his dandruff and gives him pills that make his groggy and don’t help all that much. If he scratches his skin just a little in a few seconds a huge red streek appears. His doctor doesn’t seem at all concerned about this. Do you have any suggestions at to what he should be doing? Thank you very much. It is only he and I alone in the world. The last time a good doctor checked him he was pre diabetic and he never really feels good.