Baby will only sleep when held

Mallory
My son has been diagnosed with reflux so we are dealing with that with medication but since dealing with this he's started refusing to sleep in his crib.  Even if he's fast asleep the moment he realizes he's not being held he's awake and screaming. Any suggestions on how to get him to accept he can't be held 24 hours a day?  I'm getting so exhausted I've caught myself nodding off and almost dropping him so clearly being held isn't in his best interests. I've tried standing by the crib until he falls back asleep but seriously the second I leave the room he loses it. It's the craziest thing that he seems to know I'm gone when they aren't supposed to be able to see that well.