When a baby chews on the nipple while breastfeeding, it can be painful and frustrating for the mother. Common causes include teething, exploring with their mouth, a change in milk flow, or discomfort. Solutions include adjusting the baby's latch, offering a teether before feeding, being mindful of the baby's cues, and gently unlatching if chewing persists. Consulting a lactation consultant can also provide personalized guidance.