As a GP and father of three boys all healthy (thank goodness) I would like to pass on my thoughts about colic. It is so common as to be regarded as normal behaviour and if your infant misses it count your blessings.
The new baby is used to perfect comfort in the womb so the first year or two can be quite a challenge for them to adapt. Thus they will scream if tired or hungry or uncomfortable in any way. The bowels need to adapt to the business of digesting food whether breast or bottle milk and this will cause mild abdominal discomfort - ie colic. Nothing can really remove this mild discomfort and after a while the baby gets used to it and the colic/screaming stops. Therefore although it sounds harsh they have to learn to deal with it. This means that being anxious about it and trying desperately to reduce the distress is probably going to make it persist longer and cause the poor parents a lot of angst. No baby has come to harm from it and they are much tougher on the whole than their parents. I remember admitting a screaming 5 month old one christmas afternoon as his parents had blended up a normal christmas dinner and fed him that from a bottle! He created for hours until he had digested it then was back to his usual happy self..