My Schipperke had a similar problem following a visit from another dog (relative from another state). The vet eventually said it was a combination of Low Thyroid combined with a flea problem. We used her monthly flea med. (remember to always wait 3 days before bathing and 3 days after before applying.) Many people bathe their pet then apply flea med. Instead of waiting 3 days after bathing before applying. This took care of our problem. I also applied some mild hydrocortisone cream to ease what seemed to be itching and to moisturize her skin.
