Awe...poor Chester. Like Marci said, if he already has his pain meds, just keep giving him them on the regular schedule the vet said too. My Rudy was out of it but not whining when we brought him home after his neuter. He did sleep all the rest of that day and night. The next day, you'd never know anything happened to him. So I hope that puts your hubby's mind at ease.
Feel Better Soon, Chester.