A couple of months ago I went to the hospital for severe pain and they ended up giving me fentanyl. I'm not sure how much they gave me, but it was probably a standard dose or even lower than standard dose. Could this one dose have fucked up my tolerance? *I've used painkillers like oxy and morphine before and after, but not enough to get much of a tolerance. Ever since that hospital dose though I haven't been able to achieve such a good high.