Hi Jenna,   Oh my goodness, your coworkers sound rather frightening (and perhaps annoying).  The good news is that you will be seeing a neurologist very soon.  This doctor is one who can help figure out what's going on.  Be prepared for more testing, but you will be okay.  I can understand your fear as I've experienced it before too.   Regarding your vitamin D level of 15.  Your neurologist will probably want you get that level higher.  Mine is now somewhere in the 62-68 range.   Please come back and let me know how your visit with the neurologist goes.  Hoepfully you will have a few more answers then.