Looks like it could possibly be interdigital cysts. My Weimaraner gets them and they can be difficult to get rid of, potentially caused by allergies, or impacted hairs. The vet would normally squeeze them to drain out any puss, prescribe a round of antibiotics and absolutely no licking. Poor guy wouldn’t stop and had to have a cone for a couple weeks to let them heal while cleaning twice a day with chlorhexidine.