I would take him to the vet and get blood work. I recently learned that vomiting should be rare and can be the sign of a problem, especially if the cat is losing weight.
At the start of December my cat (Roo) began to vomit regularly and I realized he had lost 1.5lbs (already skinny to begin with). I took him to the vet and his blood work showed high liver enzymes (AST, ALT) and high eosinophiles. All else was normal. He has a history of skin allergies and...
