Thank you for the reply.
Being a young male cat, of course we have to be worried about urinary obstruction. Not all obstructed cats will be painful, especially early on, so that doesn't rule it out, but most often they will be exhibiting other symptoms like frequent visits to the litter box or licking of the genital area.
The other concern in a young cat that is vomiting that frequently is a GI foreign body obstruction. Young cats are more likely ingest things they shouldn't and that can often times lead to an obstruction. Of course, there are various other things that can lead to vomiting in a cat, including metabolic disturbances like kidney or liver disease. Intestinal abnormalities, like inflammatory bowel disease can also lead to vomiting, but not usually that acutely. Additionally, cancer can cause vomiting. It is less common in younger cats, but not impossible.
Your best course of action is to have him examined by a veterinarian as soon as possible. If he continues to vomit today, I would definitely seek ER services. There is really not much that you can do for him and home other than to offer frequent small amounts of water to keep him hydrated.
I hope this is helpful. Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please reply so I can clarify for you.
My posted replies are for general education only and not meant as a diagnosis. Only after a thorough veterinary examination can a diagnosis for your pet be made and specific treatments be advised or medications be prescribed.