Question for Min Veterinary Clinic

Hi doctor, my kitten is 3 months old today. His name is Leo male cat. He got vaccine last week. He vomited June 3. I took him a vet clinic he got shot for fever for two days. After a week, he seemed very weak, didn't eat much. So I took him another vet. He has worms problem so he got dewkrms medicine June 16. He got weight gain a bit. Leo has chronic vomiting since June 2. He vomited and nausea when he eats. What shall I do? He is very small now. He wants to eat but he is afraid to eat.