Can Drop In Xanax Dosage Trigger The Recurrence Of Panic Attacks?

I have been on Xanax 0.5mg qid for more than twenty years now. About a year ago the doctor lowered it to tid which I tolerated. And two 2 days ago he lowered it to 0.5mg once per day. I suffer from anxiety with panic attacks and worry that this drop in dosage is to much and I will be having panic attacks again. I called the doctors office and told them of this , but I am not getting a reply. What do I do?