Problem analysis: Babies must have a correct posture when breastfeeding, and they can take a sitting position, a lying position or a standing position. The baby's body clings to the mother's. First stimulate the baby's mouth with nipples, and put the nipples and most areola in the baby's mouth. This feeding posture will make mom feel no nipple pain!
Suggestion: the baby can only lie down and eat milk. I think it may be that your posture of holding the baby is incorrect, which makes the baby unsuitable, so you don't breast-feed. If the baby has oral problems or indigestion, you won't breastfeed. Adjust the feeding posture appropriately and observe the feeding situation!