Welcome to Yorkietalk. It may very well be the helicopter that she is so fearful. My little girl, Ashley, started acting strangely about a year before she passed away close to her seventeenth birthday. The behavior changes were subtle at first, but then she began pacing a lot at night, and her anxiety level was high. It turned out it was the beginning of Canine Cognitive Dysfunction. It probably isn't what your little girl has, but I'm attaching a link to a diagnostic test with a checklist of the symptoms. Ashley was put on Anipryl, and it helped her anxiety.
http://www.cdsindogs.com/PDF/cdsindogs/ANIPRYL.pdf