Strangely loud noises coming from dog's stomach...

Species: Dog Age: 7 Sex: Female, Spayed Breed: Border Collie x German Shepherd Weight : 51lbs Clinical Signs: Recently (the last 6 or so weeks) her stomach has been making the loudest sounds I've ever heard. It wakes me up at night. She has off and on runny stool. She is usually a savage for food and some mornings won't eat her breakfast, or any food offered. Eventually she comes around and eats it. She has had bloodwork to look at her kidneys and pancreas, they all came back normal. She has been tested for parasites. Came back negative. We moved 3 weeks ago (which she seems to have adapted completely fine). The vet assumed stress. She has been on HILLS digestive care i/d stress for about a week and a half now. We have also added the fortiflora trial packs to her food. There has been no change and her stomach still grumbles loudly. Her stool is still soft. History: She had crystals in her urine at approx 2-3 yrs of age. A prescription diet fixed that problem and she hasn't had them since. She has had 2 bouts of what the vet thought to be a "gastrointestinal flare up"... after antibiotics and an anti nausea vaccine, all returned to normal. This was approx 3-4 years ago. I realize the details are vague and she cannot be diagnosed over the internet... I am just hoping for some insight or any suggestions as to what (if anything) else she should be tested for? Or do some dogs develop something similar to this as they get older? General Location: Southwest, ON