I find it annoying when the vets do not listen properly to your concern! Is your dog any better? My dog, CJ, gets an upset stomach every now and then and so I bought a bottle of Plantaeris for him that I keep as part of his first aid kit. Plantaeris is a herbal formula and is highly effective in treating the symptoms of dog diarrhea. It helps regulates dog’s intestinal functions as well. It might be something for you to look into, especiallly if you dog has had diarrhea for over a month. Here is the link: Dog Diarrhea in Dogs - Canine Plantaeris Natural Treatment