Sorry your poor baby had a tummy upset after his vet visit.
Did he fast before the tests and did not eat for a long time? That can cause acidy stomach issues in some dogs...like mine! He could have just been very hungry and ate too fast, and regurgitated his food?
If he tends to have GERD, Pepcid does a very good job at controlling that.
When my dog went in for a dental I was worried about the long time before he ate, so the vet gave him a shot of Pepcid prior to surgery and he was fine after the dental.
Sometimes a new bag of kibble can cause tum upsets as the quality control in some dog foods leaves a lot to be desired.
Is he eating his dry food ok now? Hope he is better now.