cysts in between toes

My dog gets cysts in between is toes
2-3 times a year and I am thinking it may be seasonal allergies

Has anyone had this happen to their dog and what do you do about it.
I have him on herbs (from herbalist) and I give him a benadryl at night
one of the cysts are scabbing but a new one appeared!!

I don't want to take to vet cause it will cost $$$ for medicine and I really hate having him on chemicals.

any advice would be appreciated!! thanks