My poor baby must not feel good.... He's been fighting sleep all day and squirming around when I hold him, crying when…

My poor baby must not feel good.... He's been fighting sleep all day and squirming around when I hold him, crying when he gets sat down, and not eating like he normally does. I don't know what to do. He has no fever, no spitting up no constipation or diarrhea. He just seems uncomfortable like maybe gas pain???