Clicking/clucking sound when nursing

I use a nipple sheild to nurse my daughter, never had any issues. Randomly yest she started making a clicking/clucking noise when she nurses, like she’s breaking to suction/seal. After a while it hurts me... I’ve tried taking her off re latching her, different positions, not using a nipple shield...nothing seems to help. I definitely feel she’s not emptying my breast. Ugh very frustrating. Anyone else had this happen?