V and D can lead to dehydration and together are serious.
The cause will not matter, if the cat deteriorates.
See your doctor today, please do not delay.
Dr G
I should say in addition that the cat has attempted to eat a few times but cannot keep food down for more than 20 minutes. He is not exhibiting any pain or lumps or anything in the abdominal area - at least not that we can tell by picking him up etc.