Awww Britt I'm so sorry to hear Mr. Jackson is having belly troubles. At least at the vet, he's in the best care. Granted I'm telling you that and I know darn well that I would have been bawling my eyes out if I had to leave Gizzy too.
You did the right thing, I'm glad that you were to quick to get him in and that it sounds like an acute case.
Sending hugs and Gizmo licks your way! Keep us updated!