Is Flaxseed oil and Fish oil too much for my American Pit Bull Terrier?

He's 60 lbs. I currently give him fish oil for his coat and skin but it doesn't seem to be helping. He still has really dry skin and he still itches a lot. He's been tested for all skin issues including demodex and sarcoptic mange but has tested negative all three times. Skin scs have shown nothing. Vets don't know the source of the dry skin and itching. He is currently eating Blue Buffalo dry and Wellness canned and was previously eating Evo. So I know for a fact that the food isn't the issue. I've askied his vet this question but she gave me the answer to everything but the question asked. I'll ask her again on tuesday when I take him in for his shots but until then I was hoping I can get somewhat of an idea of what the mix of supplements do. If he's given both of these supplements what will happen? I'm looking for answers that'll help. I don't want to hear stop being irresponsible and do what's right for your dog. I