Tropiclean has a great oatmeal tea tree shampoo.... could be something as easy as that.....
  Oatmeal & Tea Tree - Medicated Shampoo 
Riley has environmental allergies and had dry skin and the 
vet told me to give him fish oil.
I got some Nordic Naturals Omega-3 Pet in the liquid form from vitacost.com
I told him I occassionally rub coconut oil on his belly and he said he 
would benefit better from something orally.  
Nordic Naturals Omega-3 Pet? -- 2 fl oz - Vitacost