Silent puker

Ok parents ! I have a 15 month old and a 10 day old baby. My 15 month old slept on me for about a month. My 10 day old is following in her footsteps because he too is a silent puker. I'm terrified to lay him flat incase he were to get sick and choke. And I'm scared to lay him in the mommaroo, rock n play or bedside halo. Yes I am a super over protective mom but they're my babies and my whole world. The puking has been very minimum the past 2 days but when he does get sick I swear he's getting rid of every drop of liquid in his whole body. It's terrifying and he has trouble clearing his airways and I panicked. What are some helpful advice, hints or words of encouragement?