2young4bones,
your own suggestion is the very best. Repeat the urine calcium. I'd stop D altogether in anticipation of the test.
You may have high free lambda because you are overworking your kidneys by tasking them to get rid of all that calcium'.
D enhances the absorption of calcium.
I'm not one of the resident experts that you have called up in your post. But I want everyone to at least try Forteo or Tymlos because I see them as the best medication available. They clear your system quickly so you aren't trapped by months of side effects. (Unless a person make the admirable, but mistaken, amazonian mistake of tolerating side effects)
They do raise calcium levels transiently. The temporary raise in calcium is an essential part of the mechanism by which these drugs work.
When you ask for the repeat 24 hour urine, you might also ask for a repeat D, as it can stay in your system for months, a parathyroid level. And P1NP to accompany the CTX.
Few PT are trained in the dangers of exercise for low bone density patients. And it differs for individuals depending upon where the lbd is. But if you have a trabecular structure successfully bearing the weight of life and then you remove a few of the struts, and then you raise the weight it has to bear cognizant that there will be bone muscle crosstalk, when you reach the peak weight that your muscles can bear (imagine weights held high overhead) your bones with all those missing struts might just collapse before hearing any crosstalk.
Your CTX is high--higher because it has to remove the damaged bone from the fracture.
Low bone density makes us think we need to stop the loss. The cells that CTX represent are attracted to damaged bone. Don't we need CTX to remove damaged bone. Wouldn't it be to our bone's advantage to increase the cells that replace the bone represented by P1NP.