Help! Sex hurts

So, my boyfriend has a long one 😐 and every time he goes deep, not too deep, it hurts so badly to the point where we can’t continue to have sex. I was never like this & out of no where it starts hurting when we have sex. I feel so bad having to stop. I also tend to blend every time after sex and I’m not sure why. I have gone to see what’s wrong and they say it’s normal but the thing is I was never like this. Any tips?