Try cutting back on the purées! For the first few months it’s really just to introduce to solids/check for allergies. We started a week before my son turned 6 months as well and while I was working my husband was also giving him purées when he’d already had them for the day. I think it’s too much for them to process right away. We stopped purées for 2-3 days and just did the breastmilk like normal. He finally pooped and now we’re doing well. I’d say 1-2 times a day in small increments. And just make sure he is also still getting same amount of breast milk/formula as before!
Maybe try to cut back on the amount of purée at feeding times, and try to isolate the ingredients fed to the baby to gauge what might be upsetting his stomach. You can also start a food journal to keep track what the baby likes and can tolerate. And of course consulting the pediatrician and some research on the effects of the food groups on your baby may be helpful.
i read somewhere that if you’re giving solids you should also be introducing small amounts of water to help keep everything loose and to ease the constipation
What are you feeding him?