My dog keeps licking his paw

It might have hurt it or a cut you should ask your vet

There is probably something in it like a thorn or just something stuck inside.

Okay thanks I will check that out 👍🏻👍🏻😉😉

There could be several reasons for it. Allergies, anxiety, OCD, injury or habit. I would first check the pad for injury then get a cone for a week or two to stop the behavior and see if your dog resumes afterward. Even with consistent correction. If he does trying switching to a different type of food. Natural Balance, Blue Buffalo and Wellness are all really good brands that are not crazy expensive. Try for something without chicken, duck or turkey. All are pretty common to cause allergies. Lamb or fish is usually good for dogs with sensitivities and all these brands have limited ingredient varieties. My dog has a sensitive stomach and is doing extremely well on Natural Balance Fish and Sweet Potato. Your dog also seems to be some cocker cross (I can't tell for certain) and, in my line of work, I see a lot of them with skin conditions. Many of which are caused by allergies. If neither of these work then I would recommend seeing a vet to check your dog for a skin condition.