I don't have any info on the diet for crystals.

Wanted to comment: I often have done research on line and bring up issues with my vet. Sometimes it is not something she is aware of either. That doesn't make her a "bad" vet, in my mind. The Internet brings so much info right to our homes. Things change so quickly. We become "expert advocates" for our pets. Unless you are seeing a specialist, it is likely you will have more up to date info on a specialized topic than most vets will. Remember, they are generalists, like a general practitioner or family doctor. You are doing a great job it you brought info to the vet's attention.

Apart from that, when you don't have confidence in your vet, and something other than the routine develops, it is a frustration!

Paws crossed you find a diet which will work well going forward!