What could be wrong?

For the past few days my son will just start scream crying just randomly, and it’s not a cry that he needs anything its more of a cry he’s in pain, we think it’s his tummy, but what do you moms who have had this happen think it is? Or anything that might help? Even when the bottle is in his mouth he will just start screaming...he’s only a moth and three weeks old...I hate seeing my baby in pain. He has pooped and he’s farting and burping really well so I don’t think it’s gas...anything?