Miniature pinscher skin problem

Question
Hello. I have a 10 mo old miniature pinscher and he has some
problem with his skin. His back is very dry and flaky. It doesn't
seem like bothering him at all. I took him to the vet and she did
skin test (DTM Culture? it says on the invoice description) to see
if it's mite, but it came out negative. So the vet told me to just
give him Omega oil and use oatmeal shampoo. So I did use them
for a month. Those did not change his skin condition. I tried his
food to hollistic dry food for a month now, but it doesn't seem
like helping him either. I don't know what is causing this skin
problem. (Food? Allegy?) He also fart so much and stool is loose
most of the time. Is there anything I can try? I do not like giving
him medicines that much. But if there are no other way, I need
to take him to the vet again. Do you have any advice for me and
my dog?

Answer
Omega fatty acids may take a while longer to work, so continue them.  There are some antiseborrheic shampoos that will help remove the flake.  I would also have the dog dipped with an insecticide that kills mange mites even if the skin scrapings are negative.  The DTM tells the vet if there is a fungal infection on the skin, but not mites. Sometimes, a bacterial infection can cause flaking.