Hello Mike,
It is possible to get candida from dogs, but I wouldn't start treating it with creams unless your dermatologist makes a sure diagnosis. It could be an allergic reaction, maybe not even to the dog but the shampoo he was washed with. You can try taking natural oral antifungals (like coconut oil) and high quality probiotics , but I would also suggest finding a dermatologist who can diagnose what the rash is. The worst thing you can do is try to treat one infection with medicine made for another.