Q. My dog is house trained but has started pooping in the house, why is she doing that?
A. It could be the type of food you are feeding. If you are feeding a lower quality kibble, it will be packed with fillers. These fillers will cause your dog to poop more than is necessary, and it can cause your dog to poop indoors because of the excess poop. Finding a higher quality kibble like Taste of the Wild, Orijen, or a high quality food like Ziwipeak, or Honest Kitchen, will help with that issue.
Remember to NEVER scold for accident indoors. The more you scold, the more fearful your dog is of pooping in front of you, the less your dog will want to poop in front of you outdoors, the more he will poop indoors, the more you scold... it's a vicious cycle.
Have you been cleaning messes with Nature Miracle? Pick up a bottle, and try cleaning with that instead of regular cleaner. It will eliminate the smells deep down (even to your dog), which will discourage him from potting in that spot again.
Maybe he needs to be taken outside more often, and maybe he needs to be kept outside longer each time. He should be allowed at least 10 minutes of roaming outside before he has to come back inside. Allow him 10 minutes every single time you bring him outside, just in case he has to poop. He needs every opportunity you can give him. Bring him outside every hour if he's full grown, every 40 minutes if he's an adolescent (6-10 months), and every 30 minutes if he's a puppy (2-6 months). If you have a doggy door, you should still be bringing your dog outside yourself to encourage him to stay outside longer, and poop. When he does poop outside, you should praise him, and reward him with lots of treats!