Try reading the book called 'colic solved'. Written by a paed gastroentenologist. He goes through what he has learnt in his practise and it's about 'colic' being a diagnosis by doctors who can't figure out what's wrong. Usually it's reflux and/or Cow's Milk Protein Allergy.

My son had 'colic' until i cut out a whole heap of foods from my diet. Changed baby