It very well could be allergies, but as a USED to be vet tech, TAKE YOUR DOG TO THE VET BEFORE ADMINISTERING MEDICATIONS!
Having said that, dogs should only be bathed TWICE a year. Unless they get into something really nasty or the vet says otherwise. Especially if your dog is a lab or another type of water dog. Bathing too frequently causes the dry skin. If your dog has a place they can roll in dry dirt, this will help with the bad smell most people complain about.