Can someone please help? Lewie has started scratching himself with his hind feet to right behind his shoulders… He seems to itch so much that he frequently has to scratch in mid-walk... It seems like it's really bothering him. There is nothing on his skin and no fleas (knock on wood)... We haven't changed food or treats recently, so I'm not really suspect of that. I don't really want to give him medication unless it's the last resort.

Ideas?

It can take years sometimes for a food allergy to really show itself. Any shots given recently? And while he might not have any fleas that you can find, doesn't mean that he was not bitten by one or some other type of bug/spider

One flea is enough to cause a problem. You may never see it. And so can dry skin, a big bite and many other things. I would rub a little cortaid into the area, or give him benedryl for a couple of days. If that doesn't help, you may need to vet to check. Feel the area for heat, hardness, etc, not just look for inflammation or a sore.

I had a red Basenji that had that problem pop up and would scratch right behind the shoulders too and would wear the fur away. I believe I determined it to be a food allergy.

If all else fails, a thyroid panel might be needed– but typically that is more base of and tail area, all-over etc.