Definitely check with a lactating consultant

I usually delatch and try again. Maybe your maternal health nurse can give you some tips

How deep of a latch is bub getting? Ironically, sometimes you need to deepen the latch so that it’s more comfortable for you and it’s less tiring for bub and they get more from it. Not sure if that’s a contributing factor, but you could try seeing if it helps.
You could try checking that their nose is level with your nipple to start, and that their bottom lip latches first. I’ve also heard of people putting some breas milk on their breast before starting and that helps them recognise the smell. Haven’t tried that personally, but you could give it a try.
I struggled a bit with my bub, and ended up seeing a rep from the Australian Breastfeeding Association for advice. You could also try a lactation consultant – and there are plenty of videos you can google about latching so you can try different techniques to find what works for you both.
I found doing dream feeds helped a lot too, or after a nice warm shower together. She was more relaxed and it was a better experience for both of us.
Hope you find something that works for you both. It was way harder than I realised it was going to be. Best of luck!!

My newborn has days where she latches on hard and others softer my only advice is push through the pain it doesn’t last for to long or take bub of boob and get them to re-latch until it is feeling more comfortable I don’t recommend nipple sheilds unless really necessary as they can cause nipple confusion

Use nipple shields. They are “life” savers