This is a long shot but it might not hurt to get a hair test. Cadmium is known to be a risk factor for kidney problems, lack of bone strenght and it seems to be related to ADD and lethargy/poor motivation (cat. depression).
I had this problem in my early 40's--broke my leg without contact-- and have done well after Amalgam (silver-mercury) filling removal and a couple of years of low frequent dose chelation (cutler protocol).