Good Afternoon. I Have Been In A Cycle For About

Good Afternoon. I have been in a cycle for about three weeks where one night a week I vomit violently a dark brown color. I run a fever anywhere from 102-104. It always happens at night and starts when I am laying down with acid reflux (which I have had since I was 13) I am 56. It all kind of started when my primary care doctor prescribed Xanax for me as I had not been sleeping at night. I have been on the meds for about 6 weeks. Is this a side effect of the Xanax?