There are a few products out there that you can use but you'll have to figure out what it is first.

If it's an allergy benadryl can help but you have to find out what he is allergic to and remove that from his diet or surroundings in order to keep it away.

If it is itchy or swollen again benadryl can help with that too but again if its something more than just irritated skin (hot spot or something) you'd have to get him on other meds too to clear it up fully.

If it's a lick granuloma you'll have to figure out if it is caused by boredom or by something else. A lot of things even things that are not visable can cause a lick granuloma, like little pockets of bacteria under the skin, a broken or irritated hair folicle, ingrown hair, plugged and scarred oil glands and dilated and inflamed capillaries or just caused by a simple small cut or sore.

Or it could just be a sore or cut & nothing else.

You can apply neosporin to the area if the skin is broken. It will help heal it. A small amount will not hurt the dog if he licks it off but you want it to stay on so it works. It's best to apply it when he is sleeping, before going for a walk or when he's eating a meal or a chew treat.

If it a hot sopt you don't want to cover it. A hot spot needs air (and antiobiotics usually) to cure it. They often shave the area around a hot spot. If it is a lick granuloma, depending on the cause, sometimes they can be covered with a bandage sometimes not.

To be safe I'd say you can give him benadryl and I'd probably invest in some bitter apple (if your dog dislikes the taste anyways). The vet can give you the proper dose by phone. Benadryl usually makes a dog a little sleepy so don't be alarmed if he's a little lethargic afterwards. But it would probably do him good so he's not bothering it.The bitter apple can be applied to the skin & fur around the affected area, it should deter him from licking that area.