This going to sound bizarre but my first thought was chemo meds acumulating in those areas! Don't know why this popped into my head. However I do think it will eventually calm down! Once your system clears everything. Also there the use it or lose it principle - you went from athlete to couch potato, areas that were used to exercise anre now not being used anymore. Try easing into it - but at least try to walk daily! Even do light movement of he joints to try an increase their flexibility again! Good luck!