My wife suffers from psoriatic arthritis as Phil does. Sometimes it is so painful she can't put on a pullover sweater or wear shoes. The prescriptive remedies (which aren't complete cures) such as Enbril which Phil advertizes normally last about 1 year before the body builds a resistance and the pains start reappearing. When they do they move around with no rhyme or reason.
She thinks he may be at that stage of complexity.