If the dog has an allergy to fleas, it only takes one flea bite, you don't have to havea flea problem or any fleas, but get one or two bites from a passer by.
My JRT, has bad flea allergies he is a house dog that stays on Comfortis, the flea dies after it bites him but still causes a reaction of itching and scratching.
Dub you dog may also be dealing with stress related issues, several of mine (not related) are having a very thin and dry coats right now, and it has alot to do with this long drawn out length of heat we are having (I am sure of it) If she was recently spayed, or any other hormonal issues with cause them to blow their coats, just like having pups will do to some gyps.
We have a white westie that is allergic to flea bites. The vet said one bite and it will trigger a reaction which includes bumps, scabs and hair loss. Looks just like the mange.
