6 week old crying in pain? advice and info please?

Hi, my son is 6 weeks old and for some time now after most feeds (mostly during the day) he starts to arch his back and screams like hes in pain, and the majority of the time it takes a long time to settle him after changing and burping him. He also seems to have alot of gas and also when feeding he will fuss and pull alot at my , this i think makes him more upset that he is not getting a good feed and he will stop and start crying and arch his back again...I have tryed rocking, rubbing his tummy/back and lying him on his tummy but nothing seems to be helping except letting him cry or giving a pacifier....Im not sure why he is doing this? Maybe he finds it hard to p wind or maybe he has silent reflux? this is very distressing for me because i feel its interupting his quantity of feed and he hasnt shown a particular routine in his feeding habits either...Could anyone share some information and advice please.