You could try getting the NutriScan food sensitivity test done. It's not cheap but it will tell you which foods you might want to avoid feeding your dog to see if the issue is his diet. I also recommend raw food instead of kibble. There are lots of commercial ones available that many of us on this forum feed to our Havs - either air dried, frozen, or canned. Examples: ZiwiPeak, K9 Natural, Darwin's, Primal, Honest Kitchen, Stella & Chewy's.
It is probably an allergy. Bella licks her one paw, but I do think it's more an OCD thing. I THINK wellness uses a lot of different proteins. You might try a limited ingredient dog food. The ones named above are great! If you are on a tighter budget or uncomfortable with feeding raw, Acana limited ingredient grain free is good. Bella won't eat raw so I feed her this. She loves it. Scudder had to switch off raw to this because he was getting sour tummy and throwing up in the mornings. The raw didn't sit in his tummy long enough. Even if I fed it to him before bed he would still wake up puking He also loves this food.
We had an Aussie who would lick one paw to the point there'd be tiny bare spots and once in a while a little blood. Our vet thought it was an allergy and gave us some medicine. Forget what. She lived to be almost 17 and only stopped the licking her last few years. I'm fairly sure it was an OCD thing like lfung thinks Bella's is. The Aussie only did this with the one paw and it was almost like a child with compulsive thumb sucking.