breastfeeding mommas: I have been working on breastfeeding my son and he only really latches to the…

breastfeeding mommas:

I have been working on breastfeeding my son and he only really latches to the left side, he fights the right side really heavily. but whenever he latches on the left side it HURTS bad. I noticed I have what looks like a red/purple looking bruise thing on my boob and my nipple hurts so bad. What am I doing wrong?