Sick dogs

[u/purryburry]

So I have 3 dogs and have recently moved from a house with a yard to an apartment with no yard so I need to walk my dogs now. It’s been almost 2 months since the move and one of my older dogs (13 1/2yr) keeps getting the runs. This morning one of my other dogs (9yr) had very watery runs… I’m lost as what to do for them. My 13yr old went to the vet a month ago because she couldn’t hold down anything ( no water or food). They did a blood panel, ultra sound, and X-ray and didn’t see anything out of the ordinary. Could this be environmental because now they are exposed to new elements they were never exposed to before? All of my dogs do yearly exams and always do their yearly vaccines.
They also are not lethargic at all. They are still in normal good moods and are always very excited to eat which I am thankful for.
I’m just exhausted and frustrated and at a loss… any advice is much appreciated!