Hey Moms, I need your help,

I am currently figuring out and needing advice on how to help with my baby’s flat head on the back. He’s 5 months old and loves to sleep on his back, I do turn him to the side when I wake up at night to feed him and put him back to bed, but I always find him sleeping on his back every time. I want to know if I can still fix my baby’s head and if so, any advice please? I feel really guilty about this 😔 he had a perfect head in the beginning