PLEASE HELP 😩

Da
My baby is 5 days old now and have been breastfeeding but one of my breasts have turned very hard heavy and now kind of painful it's not red just heavy and sore what does this mean? It's been leaking a lot as well. My baby hasn't been latching
On properly and he barely eats for more than ten To fifteen minutes. He bit it th other day and was too sore so I kept using th other one that's not hard and painful pls help is it still ok to feed him th sore breast or is it infected?