Three day old stopped nursing on left breast

Sasha

I'd really appreciate some advice. My almost three day old baby has been nursing well up until my milk came in and kind of changed the shape and firmness of my breasts. At least I think that's the problem.

Now he will only eat out of the right side. My left side is only getting firmer as he refuses it. When I offer him the unwanted left side, he will open his mouth wide and meet the skin in a good location, but he won't suck. He'll either cry or just lie there mouth around my breast, hanging out. When I switch him to the right side, he latches and eats.

I notice when I sandwich squeeze the unwanted breast, the nipple doesn't pop further out the way it used to. It doesn't retract either... but it doesn't pop forward.

What should I do? I've tried a warm compress. My breast is starting to be a bit painful. My pump hasn't arrived yet. Should I try to hand express? (Might that relax the breast enough to make it palatable to my baby again?) Any way to help him learn to latch onto the new rounder shape?

Thanks so much for any advice.