Even though he does this in times other than winter if you get snow, make sure you wash his paws after walks as some people put salt down to melt snow and this can be very irritating to dogs feet.
Dont laugh or think me silly, but you can buy dog booties/shoes that you may have to use in conjunction with a neck cone(to stop him from chewing or pulling off the booties) to prevent licking so paws may heal and you may have to use this in times when you go out and leave him so he does not start in on the licking again. when feet are healed and you are with him you will just have to redirect him away from this behavior, but when alone you will need to take the bootie and cone approach to prevent further injuries. Sounds like he has an OCD(obsessive compulsive disorder) maybe? Why not, this i quite common in humans. I know this may also seem a little drastic, but vets in America will sometimes prescribe Anti-anxiety medication for animals, especially cats. I have never tried this for any of my cats who have anxiety problems, but i have read articles where cat parents swear by this treatment. Just a little of the medication helps to calm the animal so it does not have these destructive behaviors.
I have one feral female cat i rescued who is very nervous and started to pull her fur out along her behind and nothing could stop her. She finally got used to her new home and the fur is coming back in nicely. We have a little purebred dog who constantly nibbles his back and the vet said to take him off any food containing corn. We have him on dry containing lamb and rice and he has canned wet food and the itching and nibbling have lessened greatly.
Dont use any human over the counter medications on his feet as a treatment or deterrent unless okay'd by your vet
as many human meds can injure and can often kill animals even the most benign ones.
Good Luck.
Mikala(aka, Cat Woman)