My 7 month old baby has been making loud breathing noises since he was 4 weeks old while in deep sleep he's had a heart cheeck and very healthy?

See your doctor. There are several possible causes. The reflux could cause breathing noises. Also, some babies have a weak airway and it makes more noises when they are lying down. Nasal congestion can cause a lot of racket, even when your baby is acting normally. Check with your baby's doctor.