Mason is now 8 months old but when he was about 3 months, he used to eat his poop. I was utterly disgusted, and I knew I had to prevent this behavior. There are tablets called "Deter" - they come in a blue box and are inexpensive. I fed it to Mason for a couple of weeks and he stopped. I also repeated "NO" everytime I caught him eating his poop.
When you scold him though, be careful because for a while, Mason thought I was scolding him for pooping, and he started to run away from me as soon as he pooped

SO I had to make sure to praise him when he pooped, and scold him ONLY when he ate it.
Good luck!