I have a dog that has developed an allergy to something (haven't figured it out yet.) He is 6 years and has always been fine. This came on pretty sudden. In the meantime I want to make him as comfortable as possible. I have some soothing shampoo from the vet but it's just something off the shelf they sell and it doesn't seem to be working very well. If you have experience with a dog that has sensitive skin or allergies, what would you recommend? How available is it? Thanks for all suggestions!