hi. my baby 6 weeks (formula fed) used to poop normal and about 3 weeks ago he started straining and crying when trying to poop for hours. he will then either poop hard or soft it always changes. i tried changing his formula but that gave him diarrhoea so i am giving him half of the old formula and half new as recommended and it stopped his diarrhoea for 2 days and the constipation and pain started again. any idea what that could be the cause or. i have a doctors appointment on the 5th so i will ask them then but i want to see what everyone else sus.