I use and love Doc Ackerman's Herbal Colloidal Oatmeal Shampoo on my Tatum whom has dry skin and allergies. It really helps and soothes her so much

It can be purchased online at Only Natural Pet
Here is the direct link to the shampoo:
Doc Ackerman's Herbal Colloidal Oatmeal Shampoo
Hope this help!