I think there is no harm in adding glucosamine and chondroitin at any age. X-rays are definitive. If you are really worried than have the x-rays.
That said: You say he hasn't been running/jogging lately. It is summer and very hot. Maybe he is just a bit out-of-shape and isn't tolerating the heat with exercise.
He may need a little time to work up to what he used to do. Just a thought.