Is the only hot spot he's having is where he is licking his paw? Or does he have others? Did the vet say anything about lick granules? Sometimes this kind of licking can become an obsessive compulsive type thing rather than actually being bothered at the moment. An e-collar along with a topical spray might help to break the cycle.
Canidae is an excellent food, but you may need to look at one that has one protein and one carbohydrate source.
I had a black headed tri fluffy rescue girl a few years back that was hypo - allergic, foods as well as environmental sources. Her pads were cracked and would bleed, crusty sores in her ears, hot spots on her body. With her we went on a couple of courses of prescription allergy pills from the vet. Food wise I put her on a fish and sweet potato food and supplemented her with salmon oil, gse, 500 mg vitamin C and an immune system supplement, along with a TBS of plain yogurt with active cultures. We saw dramatic results. After the prescription allergy series, I was advised to use benadryl for "maintenance." A new drug called Atopica was just hitting the market and it was one we discussed and I passed the information along to her new owner. Atopica is for a dog that presents with a number of allergies. It was a fairly expensive medication at the time, but showed great results.
When she went to her new home, I thought she was an "after" picture, but the last one I got a year afterwards - never seen so much fluff.
However, this wasn't her owner's first time dealing with these specific needs.
You might also want to try Listerine (yes, the mouth wash) as an astringent wipe on his legs and paws to help with the licking. It works on hot spots, better before they get open and weepy, then Gold Bond Powder works well.
Debbie