Is it a disease to feel nauseous while breastfeeding?

Patient's question:

Zero nine days
Detailed medical condition and purpose of consultation: Since the age of one month, he/she has been vomiting every time while feeding, sometimes not vomiting, sometimes vomiting, and each time vomiting a lot, which is quite alarming.
Current general condition: Sometimes having a bowel movement every two days, sometimes once a day. This time, it has been three days without a bowel movement today.

Doctor's answer:

Hello: To prevent infant vomiting, attention should be paid when feeding:
（1）Do not feed the baby when it is crying.
（2）When feeding with a bottle, the nipple must be fully filled with milk, and the hole should not be too large.
（3）After feeding, hold the baby upright, with its head resting on an adult's shoulder, gently pat its back to help expel air from the stomach, and then gently lay it on its side. This can reduce spitting up.
（4）Feed the baby at regular intervals and in appropriate quantities. Do not overfeed in one sitting.
（5）The temperature of the milk: about 50℃. Measurement method: Drop a few drops of the prepared milk onto an adult's hand to check if the skin can adapt to this temperature without feeling hot.
Many mothers simply insert the nipple into the baby's mouth and finish feeding. This method can easily cause the baby to spit up. The correct approach is to first change the diaper, wash the lactating mother's hands, wipe the nipple with a damp towel, squeeze out a few drops of milk, and then feed. Alternate between the two breasts to ensure as much milk as possible is consumed. If the baby does not finish, use a breast pump to empty the breasts to prevent mastitis. After feeding, hold the baby upright, let its head rest on the mother's shoulder, gently pat its back to expel the air it has inhaled, and the baby will not vomit. Most vomiting in babies is caused by eating too quickly or too much, or changing the diaper or going to sleep immediately after feeding. After the baby burps, let it lie on its right side. This way, even if it vomits again, the milk will not be inhaled through the nose, preventing pneumonia or even suffocation. However, it is important to prevent milk from flowing into the ear canal, which could cause otitis media. Therefore, observe regularly, and clean up any milk immediately if it is spit out. If the baby frequently vomits, it can be