It took a few weeks before my LO was nursing better after her frenulum was clipped
This. I also used a nipple shield in the meantime. It took a week of the nipple shield, followed by a week without it before it was pain-free and easy to nurse.
Have you seen an LC since it was clipped? I got some good reminders and advice on how to get a good latch to begin with, and I think that really helped us especially when it came to weaning from the shield.