Reviving an old thread that I've come across, just because I have something to add!
A close friend of ours who has a LO a few weeks younger than mine switched formulas for this reason. Her DS started crying and screaming for hours every night and her HV said it was colic. (Personally, I believe it was OT as she used to leave him up and awake for 4 or 5 hours at a time and he only ever took three 30minute naps in the day.....but anyway...) his poop started turning green, and so HV said to change the formula. She went from Aptamil to Cow and Gate, and it all disappeared instantly - poops were normal, and no more colic at night. (Although, her LO still cries all the time from OT....)
SOOO, it's somewhat of an answer!