Hi Joanne-
Which Purina formula were you feeding? How long did you give it before switching? Do you know what the fiber percentage was? I was thinking that maybe choosing a Purina formula with a different fiber level may help. My two do better with a little higher fiber around 5 or 6 percent.
Also, you need to give a food a good six to eight weeks before you know how your dog is doing on it. Unless, of course it is causing serious vomiting or diarrhea.
Have you talked to your veterinarian? Some recommend feeding a gastrointestinal RX food until their tummy gets settled down and then slowly switching to an over the counter food. I hope you find something that works. Sounds stressful.
Good luck!
