Ok, I understand. There could be several causes to her symptoms. One easy thing to do would be to drop off a stool sample to your veterinarian to rule out any parasites as a cause of the diarrhea.
In addition to parasites, we could be dealing with other causes, such as dietary sensitivity, bacterial overgrowth, pancreas problems, inflammatory bowel disease, etc. A lot of these issues look very similar in symptoms, and often are basic tests are normal.
I would suggest trying a limited ingredient grain free diet. Natural Balance makes a few. I like to stick with one protein source, such as fish and potato, or duck and potato. Alternatively, you could do a bland diet at home, such as boiled chicken and rice, and then slowly transition back to regular food. This would give the GI tract some time to heal.
I think some good probiotics are in order here as well. There are a few ways to do this. There is a human probiotic called Align that we frequently use in dogs. There is a veterinary product called Fortiflora that works well. Or you can get some good quality, cultured yogurt and put a small amount on the food daily. This will help get some good gut bacteria forming.
I hope this is helpful. Post back with further questions,