I hope she stopped playing Vball..
VTOS can be more prone to clots, so I'd suggest stopping that activity until things are resolved.

The violent jerking of the arm, or upper body, might be related, or something else.
Has she ever had a concussion or hit/accident affecting the head/shoulders?

If so you might look into upper Cervical spine (atlas/axis adjusting)
www.NUCCA.com or Up C Spine

MDs rarely check this, it is more specialty chiropractic related..