My cat just got neutered but won't rest...?

We just brought him home from the vet a few hours ago. I know he should be resting but I can't seem to get him to stop moving. The vet gave us some antibiotics and pain relievers that were supposedly going to make him groggy and want to sleep but he hasn't stopped walking around. He's really frustrated with the cone on his neck and is looking everywhere for something to help knock it loose. Should I be concerned or just let him do his thing until he gives up?