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If you can't find the psychiatrist, call her ob/gyn (many daughters go to the same as their mothers, or at least know who she's seeing). Call her GP. Get her to the hospital (you can call 911 and describe her typically violent behavior, so they can come ready to restrain her if they need to). Don't call social services; don't call the police - call 911.
It can be a brain tumor.
It can be a bizarre reaction to paxil withdrawal.
It can be an interaction of hormonal changes (particularly adrenal) with any number of things.
If she never used to be a violent person, it seems far far more likely she's having a medical issue than anything else.
Even if she used to be moody, I would strongly hesitate at the idea this is a behavioral issue and assume -- particularly since she's your mother -- that this is a health problem and treat it as such.