Hi Sandra,
I’m glad to hear that you have had your dog checked out by your veterinarian. It’s unfortunate that the blood tests are normal in that we don’t have a clear picture of what’s going on but it’s good that we have eliminated some possibilities. Some conditions unfortunately cannot be diagnosed with a physical exam and blood tests so further testing such as radiographs or an ultrasound may be needed. A few possibilities to talk with your veterinarian about would be inflammatory bowel disease or cancer.
I hope this helps!
Dr. Ryan Llera