If a baby suddenly does not eat breast milk on the left side, there are usually several situations: First, the amount of breast milk on the left side is not enough, and the baby feels hard in the process of eating milk, so it may not be willing to eat. Secondly, the amount of breast milk on the left side is more than sufficient, so the baby will choke during the process of breastfeeding and will be less willing to eat. Thirdly, during the sucking process, due to the posture and position of the baby, the baby feels uncomfortable with the left breast milk and may not be willing to eat the left breast milk. These are some of the more common situations, so the correct breastfeeding posture is also very important to help your baby suckle fully.