Thanks to everyone for your thoughts!

I spoke to another vet at the clinic who has seen Barkely, too, yesterday afternoon, and he suggested we treat the recent episodes (of vomiting right after eating) first. (That is very unusual for him.) I didn't give him food until last night, and then it was: a few pieces of chicken & rice food, wait 15-20 minutes, then a few more, wait, and when he was keeping that down, I gave him about 1/8 of a cup at bedtime. So far, so good. This morning he has had the same routine, good results.

So, I suspect yesterday's problem was due to the stress of going into the vet the day before, being sedated and getting a pain relief/anti-inflammatory shot.

However, I wonder if the previous incidents were just the usual suspects - people food, over-hungry, a little hair. Still, after reading on these forums, I am concerned about the quality of the food we've been giving him and at his age, so I will be looking into some more nutritious options. If the first pattern of vomiting resumes, the vet said to bring him in and we'll look at the other possibilities - thyroid, liver, kidneys.

Overall, his behavior & weight have remained normal, so I am hopeful that it is not serious.

Thanks again for all of suggestions and good thoughts!
Take care!