Baby won't eat properly during the day, after 4-5 mins turns head from mother and start crying. ( we fed him after 2.5-3h ) he is 2.5 months old. he eats calmly only during night when he is half awake. this last few days, after he got vaccinated?

Post vaccination monitor temperature and watch for signs of a reaction, including rash or change in breathing pattern. Most of the milk if nursing is consumed in the first five minutes. He may need some time to digest. Burp the baby mid feed and after the feeding, and offer feeding again. Supplemental formula is another option, but nursing is best for the baby. Monitor weight and growth.

If it is just happening since vaccination and he is having wet diapers, I would not worry. If it continues, please consult with your baby's doctor to check if something else is going on such as an illness/ear infection.