I have a 7 months old DS who sleeps so much better when he’s got a pillow under his head. I use quite a firm(ish) adult pillow in the early hours when it seems to help him settle better.
I know you’re not supposed to use them due to the risk of SIDs etc. But is there any other reason such as neck/back problems? If not, surely there’s no harm in putting the pillow under his bed sheet so there’s no risk of SIDs. He will sleep so much better.