4. You are experiencing pain in your bones
A vitamin D deficiency can also lead to pain in other bones in your body, aside from your back. For example, you may experience pain in your shins, your ankles, or even or forearms. This pain could be a side effect of not getting enough vitamin D.
Again, since this vitamin plays such an important role in maintaining healthy, strong bones, if you aren’t getting enough of it, it stands to reason that bone pain would be a side effect.