There are a lot of very smart, passionate folsk on Curezone so I hope others much smarter than me would chime in and speak to Vitamin D.
The word passionate is an important one too. With all the focus and attention my sweetie has had on her over the years, it is not lost on me that she went through a lot of medical specialists before one finally not only had the skills to diagnose this situation (very low Vit D), but he was passionate about working with her towards discovery of a resolution. Very few docs do that. As mentioned prior, it is beyond me why ortho docs who are about to deal with serious bone surgeries (in her situation, joint replacements), and not scan for D, and other things. It just boggles my mind because I see how important it is, and what can happen when these levels are deficit.
So... hopefully your hubby's doc is knowledable, and passionate, about learning and discovery, as well as the patient and the patient's other half, that being your husband and you. My wife and I have faced several impossible, wheels off, where everyone throws in the towel situations and I've become extremely practiced at when to remain neutral, when to back off and listen like an invisible owl, and when to dial things up to the intensity of the sun, all combining to make things work.