Maybe try some lanisoh on a breast pad, put some water on it, and freeze overnight. It really helps me to relieve the pain of sore nipples. Makes you jump at first, but it feels great after that. Still receiving support from a breastfeed network here atm, so would definitely recommend seeking some help. There is the national breastfeeding network you could call, 24/7.
One of my nipples got so sore at the start I had to use one side to feed baby and the other side to express with the hakaa. My friend recommended I use silver nipple cups with a tiny bit of breast milk in them between feeds. It really helped with the soreness and pain. I would 200% look into it. After a few days I was fine and never had a problem since. If things carry on I would also check with a lactation consultant x
It might be that because you used nipple sheilds you nipples never toughened up and got used to it. My midwife said it the early days that it should only be uncomfortable when they latch initially and not for the rest of feed. Lansinoh cream helped me. But might be worth checking in with a lactation consultant to check latch if the pain persists. X