Has anyone had issues with formula causing constipation in their LOs? I think this might be happening with my daughter, but I'm not sure. She is 3 months old and since being on formula only poops once every other day and it's dark green (I'm told this is because of the iron in formula). The pediatrician says that the frequency of poop is fine.

However, she seems SO fussy and refused to nap. Yesterday she was up from 6:30am to 8:30pm and slept for a total of maybe an hour. And the rest of the day she was really angry and crying/screaming hysterically. I realize this might be down to a 3 month growth spurt, but perhaps it's that her stomach is upset? She does sleep well through the night, which complicates matters.

Has anyone else dealt with this?