I am so sorry to hear he had such pain.  Poor baby!   I hope he's better today.
 
You mentioned that you thought your cats' neuters went better 'cuz they stayed overnight.  My cats all were at the vet's from 8-8:30 until 4:30-5 or so with surgery at noontime and they were all different...had 3 littermates done the same day with varying degrees of grogginess and from showing a bit of discomfort to acting perfectly normal...and a 4th...a feral, who jumped out of a near-second-story jalousie window during the night after his neuter.  To me, they seem to react in their own way...and I am really hoping your baby is feeling completely normal in no time!  
