12 month having problems pooping?

Mine had the same exact problem. The only thing that fixed it was when the doctor reccommended something that helps, his doctor told me to put the thermometer in his bum bum like I am taking his temperature, when the temperature beeps then take it out, then do it again if needed. My lil one had so much poop come out it was unbelievable. Your lil one will feel so much better once it is all out. At first I didnt want to do it but when I did baby felt so much better. I guess doctor knew best. Also, I made a mistake by not putting anything under or around him, poop flew everywhere so make sure you do. If you want call his doctor and they will confirm the technique for you because I thought it was very odd, but what you are describing my baby had the same thing, poor lil guy was backed up. Good luck hope baby feels better soon !!