Need advice please

Cheryl • So blessed
Hi mummies. My little mum has alot of spit in his mouth it almost looks like hez foaming at the mouth sometimes. He chokes on it wen hez sleeping on his back sometimes. He is having wind pain but i dont know what to do about all the extra saliva. Doctor said its normsl just keep him upright after feeds which i do an make sure he burps. Any suggestions ? Please