Tuffy went through the same thing last month...we travel all across the US so he was in all sorts of climates & we thought it may've been that. The vet gave him Metroidazole & like you had us feed only chicken & rice but also had us give him baby immodium ad. We never did find out what the culprit was but I share your agony over the poor pups' messes since we travel in a semi truck
Talk about fun! NOT
Hope Tink feels better soon but you're not alone; I noticed when Tuffy was sick there were several others with the same problem so it may have been a virus he picked up.