[Ellie May]

Vet can't diagnose environmental allergies just by an exam. Might be time to move on to someone that will serious look into this... Chewing feet for hours is extreme and it's a major quality of life issue.

You can give an antihistamine, but it's not effective for all dogs and isn't going to do much of anything for food allergies. You'll have to find out if it's food, environment, or fleas. The management of each is different.

Skin allergy testing followed by allergy shots or even Atopica would be a good idea if environmental (sometimes the testing is skipped and a trial of Atopica is done).

Any fleas around there?

Less likely is food allergies, but still very possible. You can do an elimination diet. I would not add products in with ingredients that could make things worse.

Steroids work very well for allergies. Long-term, they aren't a great idea, but sometimes for short-term they are needed. He is in an itch cycle. He chews because he's itchy and then chews more because he made himself more itchy, etc., etc. This can usually be broken with a steroid injection (you'll have to talk to your vet about whether or not this is right for your pup. this is what I choose for my pup when she is like that. it just isn't fair to her to let it go on). However, that only lasts for a few hours to a few weeks (depending on which one used). You can also get some to give orally. Sometimes it settles things down for longer. Just depends. This isn't something done by itself. It should be paired with testing and/or elimination diet and/or a safer drug so it doesn't have to be used long-term. Also though, dogs have to be off of steroids for a few weeks before environmental allergy testing can be done.

It sounds like it's time for a new vet unless they offered to go further if the Benadryl didn't work.