Massive hair and eyebrows loss after botox. What caused it, and how should I treat it? (Photo)

It's exceedingly unlikely for the Botox to be the source of your hair loss.  An in-person evaluation by a dermatologist would be the most accurate way to diagnose the hair loss.  If the diagnosis is in question, a biopsy may also be performed.  

I am sorry to hear about the problems that you are having.  I am not aware of reports of hair loss after Botox treatment.  While I don't question the problems you are having it is possible that the timing of symptoms with the administration of Botox is a coincidence.  I would recommend seeing your primary care doctor for an evaluation.  Things such as thyroid disease and systemic problems can cause similar problems.  If it is related to the Botox the symptoms should wear off as the Botox wears off.  In rare instances a stress to the system can cause significant hair loss.  The hair commonly regrows but can take weeks to months or longer to reach its former length.  I hope you begin to recover soon.  Best Wishes,Cody Koch