older dog, is it allergies?

It’s really difficult for a sitter/walker (who are the most active participants this forum) who has not seen your dog to diagnose it online. If you’re doubting the vet’s advice, I’d suggest going to another vet for a second opinion.

The medicated shampoo would help kill any infectious organisms or parasites.As a side note, some infectious parasites are transmittable to other pets And to humans. There are medicated waterless shampoos and wipes that might help extend the time between baths, although they really can’t clean as well as a fully medicated bath.

Apoquel is usually a daily long term RX. Instead of Apoquel, Another option to used treat allergies, which I prefer is a C.A.D.I.(canine atopic dermatitis immunotherapeutic) injection, given by vet, monthly.

A Cytopoint shot worked like magic. I've never seen any dog stop itching on Apoquel. Cytopoint is not a steroid, but a biologic. Initially they give about once every month to 6 weeks. Now he only gets a few times a year.