6 month old pukes/spits up when pooping. Normal?

Keisha • 23 🌮🍷 Momma to a baby boy 💙 Girl due Nov 2019🎀Wifey to Mr. J 🥰💑👪

Been happening the last 2-3 days, he strains to poop his face goes red and he just grunts and growls really loudly. His poops are like adult poops now since eating more solid foods. But he also spits up if he recently ate or even pukes. What’s causing this? Is it normal? I know too much iron has a lot to do with constipation and harder poop, it is a light green/brown colour. I heard to feed foods that start with the letter P to help with constipation (is this even constipation since he is pooping?) so should we feed him more peas or peaches?