I'm not a medical doctor, but if I were you, I'd look for another one. Preferably a doctor who cares more about addressing the root cause of your problems rather than just prescribing pills. Not much difference between that & what you've been doing.
BTW - benadryl in particular is hard on the liver, and often builds tolerance very shortly (I've read that it can approach placebo results when used as a sleep aid within 3 days).
Acute insomnia after quitting is common, but you often can't sleep after that for other reasons... namely because your mind is no longer numbed to the reality of your life, which for many of us is scary after we've spent so much time messing it up. 'Normal' people call it worry... and the best way to cure it is to solve the problems you're worried about. Not take another pill.
BTW - What I've found to be helpful when I can't sleep is to get up & get something I need to do done. Just lying there counting the hours you might get to sleep if you zonked out right now (which never happens) is the worst thing you can do. You're going to be awake one way or the other. Might as well make it productive. And you'll very likely find that after doing so you are able to get some rest.
Sometimes we need to get our priorities straight. This is your life - literally - on the line. So with that being said - is it possible for your family to pick up the slack over the next week or two (or three, or however much it takes) to make life easier for sleepy-you?