If baby bites then just teach baby not to bite by removing baby from nipple and tell baby sternly not to do it. After awhile baby will know. Some babies never really bite anyway. My dear daughter has 8 teeth now at 15mths+ and i'm still bfding her. Now and then i get some cuts on my nipples when she's sleepy and didn't latch properly but it really isn't often and the pain's bearable... maybe i think the pain's ok coz last time when i just started out bfding her she gave me hell and i couldn't even recognise my nipples... so ya now the pain is nothing... haha.
Anyway, some baby who are used to the nipple will reject nipple shield coz harder to suck... If really very painful now, pump out and feed? Would that be feasible?