Plain Benadryl can be used in dogs.
Paw licking and skin chewing is often a sign of allergies. You may see red staining to the fur in the licked areas or raw spots where the dog chews itself to the bone.
The skin itches from allergies, the dog licks and chews trying to soothe the itch, making the skin raw and allowing other infections to set in which may itch even more.
You can read about allergies and dermatitis in dogs here
Dogs can develop allergies to foods, and to inhaled items, and contact allergens such as rug cleaners, cedar beds, or chemicals including lawn chemicals or even flea bites.
You might want to try a different dog food that has no ingredients the same as what you feed now. Diets of Fish and Potato, venison, or rabbit etc. where the protein source is new and there is no grains in the food can work for many dogs for example.
You might want to see if some plain Benadryl helps with the itching. A common low dose is 1mg per pound of dog every 12 hours. If you choose to use that please read here about cautions
Or you may want to consult with your vet and consider doing allergy testing.
You may want to try a Chlorhexiderm shampoo from the pet supply store in case the problem is a bacterial skin infection.
Dogs can also have low thyroid level issues and that can trigger skin allergies.
The vet can check for that with a blood test.
If your dog is not on a flea prevention that might also help. Just one flea bite can make an allergic dog itch all over.
Hope this helps you!