Indeed--resting the affected body parts is essential. Also, I've found Ibuprofen very helpful when things get too stiff to be comfortable.
And definitely get a professional opinion. Anything that doesn't pass off in a couple of days is worth having an expert look at. My doctor's opinion was that I was just getting older (he's right about that--I still am!!!) and losing my flexibility. "Use it or lose it," he said, and so, within reason, that's just what I've been doing. My dad's still water-skiing (slalom, no less) and he'll be 74 next Sunday, so I'm hopeful about the prognosis.