Colic or reflux

My one month old, has been really uncomfortable all day and has been on and off crying all afternoon/evening. He’s been crying after his feds, when we try and burp him, he’s arching his back and what seems throwing himself back. He’s spits up some milk. I’m wondering if anyone knows if it is colic or reflux? Im going to call the gp tomorrow as he’s been like it that last couple of days