Congrats on quitting smoking!
I am concerned that you have been taking xanax for 4 years. One is usually not advised to go longer than 14 days in a row on them because they are addictive, just like sleeping pills (which carry the same warning).
That being said, I have had an as needed prescription for xanax for the past 6 years (but I only take a few a month and not more than 14 days in a row ever). I also take it for sleeping problems mostly. It is the only thing that ever worked for me (aside from a few benadryll), the sleeping pills that I was originally prescribed did not work.
If you haven't already tried benadryll, you might want to give that a go as it usually works for most people, even if you have to take the upper limit on dosage. Plus, it is good for this time of year anyway.