using a wedge in crib for baby while sick?

I've seen some of you moms mention using a wedge in their babies crib to help keep them propped up while they're congested. My son is starting to get that snotty congestion AGAIN (Just went through this right after Christmas.) He ended up getting an ear infection before due to the congestion and I'd love to prevent that from happening again. But how do you get your baby to use the wedge??? My son moves all around the crib!! I feel like I'd probably put the wedge in and he'd move to the other side lol.