Isn't there a spell called something like "Bitter Taste" specifically for use against things with bite attacks? I believe that when cast on a character, a creature biting that character has to save or become nauseated. I'm pretty sure something like this is published, but I can't find it.
As for actual regurgitation, though, I think one of the compulsion enchantments is the only way to go by RAW. Especially Stream's suggestion of using Entice Gift to retrieve a friend by way of the technicolor yawn. That's brilliant, spectacular and disgusting all rolled into one glistening steaming mess!
If you want a mechanic, though, it would be easy enough to just make it so a save vs the nauseated condition that fails by (for ex) 5 or more means the creature vomits, if it is capable of vomiting.