Thanks girls.

I don't think it's thrush, have had that before (twice) and I can see where he's taken the top layer of nipple skin off. It's an achey feeling after feeds but doesn't persist for hours or anything. It's made worse cause he's doing a lot of grabbing and hitting and rubbing his face in our chests atm

I think it is a combination of his new teeth and attachment/position. He has always fussed more on my left and is more prone to turn his head while still attached and pull off that way. It's hard to know when he'll do it cause sometimes it's at the beginning (waiting for let down he'll come on and off) and sometimes at the end when the flow slows or he's had enough).

I might try lying down, (was never comfy in the early days but he's bigger now) and I have been stopping the feeds if he bites or pulls.