I'm sure glad my vet keeps them overnight...I wouldn't know what to do if my baby boy (who got neutered already) was crying...I'd be a mess!
Poor baby, just give him lots of love & his pain meds should alleviate any pain, make him comfy in his bed & keep his surroundings nice & quiet.
Hope he'll feel better real soon...Momo was running around the 2nd day, I had to carry him to prevent him from hurting himself!