What type of cry is this?

I have a 7 week old son and I was told by the doctor he sounds colic. He'll cry and that will come to a screaming-very upset cry, he's kicking his legs, flailing his arms, his diaper is changed - that doesn't help, we pick him up - that doesn't help, we try a pacifier - that doesn't help either, we try singing/talking to him - that doesn't help. Some people tell me he has gas pains if he's screaming and kicking his feet like that. Since i'm nursing when he cries like that i'll put him to nurse even though he just nursed an hour or less ago and he will stop crying and nurse. Does that mean when he kicks his feet and screams it isn't gas pains??? I feel like I can't determine when he has gas and is in pain.