Talk to Gastroenterologist on Constipation With Vomiting

Aoa my baby is 9.5 months old. He was teething and then we have changed his milk from meiji FU to fresh cow milk. He had the constipation and vomiting. We shifted back to meiji but constipation and vomit still exist. He passes stool a hard one with difficulty then had vomits. He is having soset for vomits and had one drip as well. Kindly advice what to do?