sleep help

if I just keep putting him in his pack n play will he eventually fall asleep? He’s almost 4 months old. I don’t want to leave him to cry but I can’t do this anymore, I’m sitting in bed with him sobbing because he won’t sleep unless I’m standing up rocking him. Im so tired. obviously im not in any position to attempt this tonight. But If I pick him up to calm him down when he cries but keep putting him back down will he eventually sleep or will he just cry the entire day and night?

Edit: we have bedshared almost this whole time but lately he has been hating that too, waking every 45 minutes mad and I can only soothe him by sitting up and rocking him. I don’t mind bedsharing but if he’s going to not sleep well that way anymore something has to give