Hi lightning05
Sorry to hear about what you are going through and the obstacles you are facing to finding treatment.
I have unfortunately experienced flashbacks as well with no notable trigger and it is alarming to put it mildly.
It's wise of you to stay away from benzo's (Xanax, Ativan etc.) and most certainly I would stay away from sedative hypnotics such as Ambien and Zolpicon as well, not only because of their potential for abuse, but also the likelihood of these type of sleep medications worsening your symptoms. I know for myself , when I was going through this, lack of sleep seemed to exacerbate my flashbacks. What helped me was an antidepressant, mirtazipine, which is taken at night and is highly sedating. It is also known empirically to kick in faster than other antidepressants. Another technique for grounding that may help is the 5-4-3-2-1 technique:
Name 5 things you can see around you ( a book, a ceiling fan, Etc)
Next name 4 things you can touch around you (a pillow, your hair)
Acknowledge 3 things you can hear (clock ticking, car driving by)
Name 2 things you can smell around you
Finally, Acknowledge one good thing about yourself
Hope this is of some help to you and wishing you the best. Know this CAN and will get better!