Sounds like you've got the right meds for it. And yes, stress can be a cause, according to our vet.
Ozzie had two bouts of hemorrhagic gastroenteritis (HGE) in four months time requiring hospitalization. (once in November, again in February). This condition is not just runny poop, though it starts as that. It graduates to just straight blood. (If you've never seen this, I hope you never do.
) It's one of the most unnerving things I've ever experienced.
We have a bottle of Metronidazole in the cabinet now and he gets half a pill if he has exceptionally soft or runny poops for more than a day.
After the initial illness, he was also on both flagyl and Pepcid.
These guys have such incredibly delicate digestive systems sometimes!