Breastfeeding

My son is almost a week old. He eats A LOT! I know breastfeeding will hurt a little for a bit but when he first latches onto my right side it's almost unbearable pain. There is a sore that keeps opening up when he eats on that side so I've started to use my haakaa and having him eat only on my left side because that side has no pain and he latches great. But occasionally he will be too fussy and I have to put him on my other side. I'm just curious if it's normal for the one side to be an issue, I've tried many positions and they all hurt.