Hi there ~
It is likely that you were having an anxiety
attack as a result of halving the dose of your lorazepam
and starting to take alprazolam which is a replacement. However alprazoloam has a very short half life. So you might need to go up higher on the dose of lorazepam, maybe not to the dose on which you were before. I hope this helps. I also think you should consult your psychiatrist
when you initiate these medications.
Take care and have a lovely day!