Could my son have bad gas?

My son is almost 7 weeks and up until a few days ago, he was the absolute best baby. He has been congested and developed a nasty little cold so he has been a little under the weather. It seems like for the past two days, even after feedings he screams and cries. He has been taking about two-three 20minute powernaps during the day and thats all. When he cries he does stretch his legs then bring them up to his chest a bit. Im not sure if its gas or is it that he's just extremely over-tired??