crib/sleep training help

To start off, my little guy has bed shared with me from week 2 until now - he is almost 4.5 months. I believe he is in a sleep regression from what the internet tells me which makes sense, at night now he wakes up and screams to be fed and does it much more often - before he would just gently stir and feed.My husband and I have been trying to get him used to his crib a bit because we would like our bed back in the next few months, so we have begun trying to gently get him in the crib for naps. We are setting up some (I believe) bad habits by rocking him to sleep and nursing him to sleep before putting him in there because he wakes up about 20 min. later and is not happy. He screams.I have tried putting him in his crib "awake" but somewhat drowsy but he just cries and screams and it intensifies as time goes on. We have tried to let him just CIO with timed check ins - but aren't comfortable with it, as he gets so intensely upset that he is hoarse and shakes for a good while after we've gone in to check on him. He also doesn't stop crying when we check on him - it almost gets worse. Just today as well he started to roll from back to stomach and is all over his crib because he is just going insane in there.I guess our challenge is how do we get him to self-soothe when we are putting him down awake and he loses it EVERY time.The rocking and/or nursing seems to be the only way he will nap in the crib.We do have a nap routine and bed routine that we do, the room is TOTALLY dark, we have white noise, it is a good environment. I just don't know what to try at this point, have I screwed up him using his crib now? Am I destined to bed share until he is a toddler?TL:DR - My kid hates his crib, screams bloody murder in it, will only sleep there if nursed or rocked to sleep first. Need help. via /r/Parenting http://ift.tt/2bcta8x