Hi,
No I definitely don't think you should just let it be. There may be something there that you can't feel, and yes, he may have a skin condition, but also, he may be constantly biting at this paw because of stress or an OCD (obssessive compulsive disorder) type of problem. Cats can be stressed quite easily--it's not like stress (worry) in humans!
Cats with this type of behavior (excessive licking/biting) are usually found to be stressed/anxious, have skin, environmental and/or food allergies, or an obssessive compulsive urge to do this, with no obvious cause.
The vet will evaluate him and give you a definite diagnosis and subsequent treatment, if needed. If it's found not to be medical, but behavioral, there are medications which can help. He also will most likely be given an injection of a steriod like Prednisone and possibly an antihistamine to relieve his symptom for the time being.
Please let me know what the vet says. Thanks!
Cher
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