This does not sound right to me at all - every dog is different, but normally the boys feel a lot better (noticeably, anyway) the next day. Was this a normal neuter or was it abdominal?
Wylie's was abd., so I don't want to compare that one for you. But Marcel's was a standard neuter - and he was with it the very night of the neuter and almost back to norm the next day - hardly phased him. I gave pain meds for about 3 days, I think.
If you think he is in trouble, I'd get him to a vet asap - post surgical dogs are vulnerable. If you truly think it's just pain - I'd go get some pain meds from the vet asap. Please keep us posted on this little guy.
