After Years Of Anxiety (not Understanding I Had Anxiety), My

After years of anxiety (not understanding I had anxiety), my doctor prescribed me Xanax 5mg as needed about two years ago. I have found that it makes me too tired during the day if I take it. I do take one every night, as it helps me fall asleep within minutes, and he said this was fine to do. Otherwise, I would be awake all night unable to turn off my thoughts. Three weeks ago I visited with him about how I was feeling.... I have been experiencing anxiety daily and even panic attacks so severe that I was forced to pull over on the side of the road because I was driving and I couldn't breathe & my chest hurt so bad. I felt as if I was going to pass out. Scared me very badly. He put me on 50 mg of Pristiq daily and said I could continue the Xanax at night to sleep. It's been 3 weeks..... I feel so serious, like nothing is funny, nothing is really too sad, etc. Although the anxiety is not as out of control, I feel irritable. I am a white female, 42-years-old. I have never had to take prescription meds until my full hysterectomy in 2011, at which time I was prescribed Estratest, which I take daily. My job is high pressure, my marriage is in repair, we just moved, school is starting for our last two children in a week (our last two children at home out of 8!!).........MY QUESTION is: Is it really safe that I am taking the Xanax 5mg and Pristiq 50mg?