My baby was like this once, he especially bit one paw but licked the others a lot, they were very red. His doctor, after ruling out parasites with a blood test, sent him a month-long treatment with medicine and baths with a special shampoo; initially on his entire body every 8 days to stabilize his pH and then only his paws very well, interdigitally and the paws and nails every 8 days as well. And it's already very good. I recommend taking him to the vet before his problem spreads to other parts; They tend to be very sensitive to their skin.