If it has been this long and he has not put his foot down it is time for an xray to see if there are any fractures just to be on the safe side. You are right about the paw pad peeling though, this is from lack of weight bearing movement as the ground would continually exfoliate the pads and this is why you don't see it on other cats. I wouldn't give him more than a couple more days. The wholes where the drain was placed will still need to seal up so that can take another couple of days and hopefully his pain we decrease by this time. If not contact your vet. He may want to try pain medication first like an anti inflammatory or have him evaluated for a possible fracture.