Probably colicy... If he is breastfed, it could be that your wife/girlfriend ate something that was bad for baby's tummy.. These things can be caffiene, cabbage, beans, anything that would normally give a big person gas will also give a baby gas. Also spicy foods are to be avoided..
If it's forumla, the baby may be in need of a burp, or maybe has a sensitive stomach... I would suggest you go to the pharmacy and get some GRIPE WATER. Woodwards is generally best as it has no alcohol (some of the other ones have a small amount, not harmful but better not to have it). A bit of gripe water can really make your life easier. If you have other questions, you can hit me up
