Help! breastfeeding pain 😩

My son is 6 days old, and up until yesterday was latching perfectly - we were able to feed for about 30 mins per breast whenever he wanted. Then, almost overnight (Saturday night), it's like he forgot how to eat. He suckles SO hard that the pain has LITERALLY brought me to tears on many occasions. When I break the latch, my nipple is squeezed flat and I am in unbearable pain, and he isn't satisfied so he is screaming and crying. When I try and pump, my nipples are so sore from him that I can pump for an hour and only get about 10-15 ml of milk even though I feel my ducts are full. I'm at my wits end - please help me out! How do I feed without being in unbearable agony?