My roughly two-month kitten, bought a week ago; the night before last at midnight it vomited once, a thin white worm like roundworm, then next afternoon vomited again without worm, just foam, then through the night vomited about ten times, sometimes yellow fluid, eating or drinking nothing, even milk vomited. What do I do?

A cat vomiting thin white worms is very likely roundworms, which live in the small intestine and stomach, absorb nutrients, and irritate or block the gut, causing diarrhea, pain, and vomiting. Because vomiting is frequent and the cat has not eaten for a long time, this easily causes pancreatitis and fatty liver, so best take it to a vet for fluids to correct electrolytes, then treat the roundworms. Treatment is mainly deworming, anti-inflammatory, and nutrition: use dewormers with ivermectin, fenbendazole, albendazole, febantel, or praziquantel, with antibiotics like metronidazole or amoxicillin-clavulanate. Two hours after antibiotics, give pet probiotics; if vomiting stops, feed a little warm-water-softened kibble in small frequent meals. Do not give milk, as many cats are lactose intolerant and milk may worsen gut discomfort and diarrhea.