Please check out this website at the University of Maryland Medical Center. It will give you a great overview of alopecia, which I think is what you have. But only your doctor can give you a positive diagnosis.
http://www.umm.edu/altmed/articles/alopecia-000004.htm
To the best of my knowledge, alopecia is not a side effect of anxiety/panic, but you should speak with your doctor about this as well.
Let us know what you find out, OK? I wish you the best and hope you find a cause and a cure.
Peace
Greenlydia