pulls off breast when still latched!

Brittney • Mama of 2 girls with baby number 3 on the way (hoping for a boy!!)
Ow! Does anyone have any opinions on how to get my baby to stop pulling herself off of my breast while still, essentially, latched on!?! This is a new development. She won't open her mouth and let go anymore. She's started to just pull as hard as she can to get off, which is EXTREMELY painful! I'll say it kept me awake during our midnight feeding just now 😰. 
She is 4.5 weeks old. And she does it all of a sudden. No signs that she's done feeding or anything. Sometimes she will re-latch, other times it's when she's completely done with the meal.