I agree with Jax08 to first have your vet check her over and take in a stool sample just in case. My husky had something like that and it turned out to be whip worms. If you've done the food changes quickly that could also be causing the up and down cycle. If everything checks out, I'd suggest adding a prebiotic for digestion, like Optagest which I give Baron as a daily supplement. For kibble, I can recommend Solid Gold which I order from Chewy. I feed Baron 1/2 Solid Gold Barking at the Moon (an all life stages kibble) and 1/2 Taste of the Wild Puppy Salmon. When I fed him all Taste of the Wild, his stools were loose, but he is doing well on this combination, so you may want to try 1/2 Solid Gold and 1/2 Diamond Naturals but do it slowly.Also it may be helpful to keep a journal of what she is eating including treats so determine if maybe there is a difference in her diet on those days that she has the diarrhea.