If the poor dog has fleas, she's probably being driven crazy by them. Get your brother to take her to the vet, to be thoroughly checked in case she has mange too, then tell him to buy some Revolution. There are other brands available too. In the meantime he can give her a bath or two, to relieve some of the fleas.
She could have a food allergy...what is she being fed? It could be an atopic dermatitis, which covers just about everything else, that she is sensitive to when she comes in contact with a certain substance. She could be bored, do you take her out a lot, or does your job take up a lot of your time? The best thing to do is rule out mange, and fleas, and then start on the diet. All with your vet's approval of course.