Ulysses throwing up.

I wasn't sure if I should put this under nutrition or health.  I came home from work and fed my boys (1/2 can each of the Weruva chicken).  As soon as Ulysses was done eating he threw up everything.  I had to go out for my bike ride and came back and there was a hairball on my carpet with yellow liquid (unusual in my house).  Earlier I had noticed a yellow spot on my carpet elsewhere that looked like one of the cats had thrown up and possibly ate it or it was only just yellow liquid.  The only one I'm sure of is that Ulysses threw up his food. Unsure of the culprit of the other two throw ups as I didn't see them.  I've never seen the yellow liquidy stuff in their hairballs.  Anyone have any idea about this?  I'm thinking that Ulysses threw up his food because maybe he was working on the hairball that eventually came out. hmmm?

I fed him again a teensy bit ago and so far he has been fine.

So any ideas on the yellow goop?

I really hate it when my Ulysses throws up. It reminds me of when  he was a baby and wasn't thriving.

it sounds like bile.  i feed my cats weruva paw lickin' chicken and they never throw it up.  the mideast feast w/ tilapia they have, but once i let the youngest eat way too much of it and the other one i think just ate it too fast because it didn't happen anymore.  i'd go with hairball.