Thanks everybody. I just got home from dropping Oliver at the vet. The vet was shocked to see how much he was limping compared to 2 weeks ago and has finally agreed to do xrays. After the physical exam he said not only did the foot need to be xrayed, but also the shoulder, pelvis and entire spine.
As a human xray tech I know what he'll be going through this morning and then the dental after that.
If we get lucky and it's just severe arthritis, and knowing that Rimadyl, Tramadol and assorted kinds of glucosamine haven't helped, what else is there to try?