My baby won’t sleep

My babe is 4months old, he’ll sleep 2-3hrs MAX and that’s only if he’s on me, I’ve tried his crib several times, No judgement. I’ve warmed it up with heating pads before putting him in there, tried putting him in it both awake and asleep, put his favorite blanket over him, footie pjs, everything. I just want him to sleep through the night or at least 5 hours, I’m at my wits end.