Be careful with the Benadryl, it can make some dogs drowsy. I would not double or triple, I too was a vet tech and have seen the drowsy affect on dogs. The Benadryl though could help the itching but not the problem.
If it were my problem, I would do my first suggestion, wiping feet clean and applying an anti itch. Least invasive.
Dog food allergy usually would make the dog itch all over.
The DE could kill more than just the bugs you want to kill. Not sure the affect that would have on your grass. Once you watered it down though, any bugs that went deeper should be fine.
Good luck, let us know how it goes.
If it were my problem, I would do my first suggestion, wiping feet clean and applying an anti itch. Least invasive.
Dog food allergy usually would make the dog itch all over.
The DE could kill more than just the bugs you want to kill. Not sure the affect that would have on your grass. Once you watered it down though, any bugs that went deeper should be fine.
Good luck, let us know how it goes.