14 weeks and won’t stop biting

I went to an LC last weekend and she helped me with latch and he was doing great! Then yesterday he starting biting my nipples again. He bites down and pulls it really hurts! The LC said if the latch is correct it would be impossible for him to bite but the latch feels good when he’s not biting me. When he does it I’m trying not to react, just place him down and give him a break. But what is supposed to be a 20 minute feeding session is turning into 45 with all this back and forth. Anyone else experience this and have tips on what to do? I’m getting so frustrated.