Have you had vitamin D tested? That would be the best way to tell if your problem is related to vitamin D deficiency.
Are you no longer taking the multi-vitamin? Lack of B vitamins can also cause dry, itchy skin. Since the itchiness went away while you were taking the multi (which would contain, both B vitamins and vitamin D), you should talk to your doctor and see if you can start it again.
Hypothyroidism can also cause dry itchy skin and even though your thyroid labs might be in range, doesn't mean it's normal for you since we're all different.
Vitamin D deficiency can cause bone pain. The thing is: if you have vitamin D deficiency, most likely, you'd have bone pain throughout your body - not having it "travel" around to whatever part just stopped itching.
You would really need to get your levels tested to know whether or not that's your problem. Talk to your doctor; it's a simple blood test.