More Possible Stomach Weirdness

Some of you may remember that a few months ago Folly had horrible tummy trouble and landed at the vet, only to 2 months later have another, slightly different, bout of stomach troubles.

About a week ago he had some runny poop but it cleared itself up before we could try anything. Thought he was just having a bad stomach day. Been trying to give him yogurt to help his tummy more often. Now tonight, for the 2nd or 3rd time in 4-5 weeks, I suspect he's thrown up at some point in the day while we're working and then eaten it back up. (Ew). I'll find crumb-like remnants and then look more closely and see a hint of a stain.

I have no idea what is causing this, since when he's been sick the last 2 times, antibiotics cleared things up, although he was also fasted and given anti-spasmodics to calm his system.

Am I missing something here? Is something horrible happening to my dog and I don't know? Or is it normal for a dog to throw up every so often?? He seems otherwise fine, energetic, and responsive. Our dog walker hasn't mentioned anything unusual going on. Our schedules have been crazy, and are only going to continue to be so, as we leave for our wedding next week, and Folly will be with Linda. Afterward, he comes home to stay with my sister while we are on our honeymoon. Could schedule insanity, although normal in this house, be causing this?

Sorry, just looking for answers, thoughts, advice. Thanks!