The thing about nalo/trexone is, that they are inverse agonists. It won't just precipitate but exacerbate withdrawal, guess thats the magic behind U/LDN but I can barely imagine what it must be like to get a full shot of naloxone while on heroin (probably they won't reverse all at once as this would cause another medical emergency, see ultra fast wd, and many ODs require multiple shots) let alone 50mg naltrexone ... applying naltrexone while in dissociative anesthesia also appears to greatly shorten the time of withdrawal, but can kill you, sometimes even in a hospital (silly me suspecting neglect of care)..
The weird one is people feeling normal on naltrexone (after withdrawing, of course).
Did you self prepare or order some ULN solution? Here ordering from US takes ages, but they sell the 50mg pills...