My Luigi had almost all of the same symptoms as Maddie when we 1st brought him home from the breeders. It was more scary and painful for me than for him, I think. My vet too chacked for all kinds of parasites and bacteria and viruses and everything came back neg. Thank goodness. She even checked for that colitis, but came back neg also. Except he had a little bacteria in his poopoo. He was also put on prescription food for awhile, and after all that testing and 2 night hospital stay, they still didn't know what it was for sure. Every now and then his tummy makes that scary sound, so I give him 1/4 of a pepsid pill.
So I guess what I am trying to say, is at least they know what it is and more of a chance to make her all better!!!! Which I will be hoping and praying for!!!! Since it sounds like she will have a very sensitive tummy, I would make sure she only gets puppy food and no human food. My vet told me the most simplist things can give them an upset tummy.
Please keep us posted on how she is doing!!!!!
Luigi sends Maddie lots of puppy kisses!!!!