I'm sorry to hear about all of your accident's, I've actually experienced the majority of what you've been through so I feel your pain. And good luck with the fentanyl, it has a much shorter half life then dilaudid, and almost lends itself to people being tolerant of it over a period of time, and giving you're history you'll probably become tolerant faster than most.

Oh and by the way, when I was burned (2nd and 3rd degree over 27% of my body from the waist up), they were giving me morphine for the first couple hours before they realized it just didn't react with me at all. So you're right, you do learn very quickly what works and does not work.

Good luck you everything bro,

-Sean