Hi Sanda,
Sorry to hear about your dog’s troubles and I empathize with your frustration. Based on your description, it would seem there is something wrong. I would seek a second opinion, especially with an internal medicine specialist. Possibilities they could look into would be megaesophagus, pancreatic insufficiency, and inflammatory bowel disease. All of these conditions can be managed but they need to be properly diagnosed first.
I wish you luck and hope that you get this figured out.
Dr. Ryan Llera