first advice is going to be - DON'T DO IT!
you're only substituting one chemical for another. sleep on drugs is never real sleep any way, as much as it may feel like it. you're better off fighting it out til you get back to a natural sleeping pattern on your own. if you start taking sleeping pills now you'll definitely get the sleep you want but then what are you going to do after you get used to sleeping on those for a week / month / 2 or 3 ? it's also never going to be as cozy as that oxy sleep, i know the feeling you're looking for and you're never going to replicate it w otc meds, lol.
i had the same thing happen after my surgery in jan/feb. trying to adjust to natural sleep after narcotic sleep sucks but starting a new set of pills only hits the reset button. eventually you have to pay the piper. if i were you (and i've been there) i would just suck it up til your body adjusts again. it may take a few weeks but you'll be happier to go that route.
now- if you don't want to listen to me i was always partial to tylenol pm. i'm sure it will work for you, but if you do stat taking them don't get on an extended plan.
my 2 cents