Hello Bruce, I'm Dr. Deb.
I recently came online and see that your question about Tom hasn't been answered. I'm so sorry that you've had to wait for a response,but if you still need assistance, I'd like to help if I can.
First of all, big congratulations on the new member of the family; I can't imagine a more perfect Christmas present:)
It doesn't take much to trigger vomiting in a cat but it's a little less commonly seen in one so young.
There are any number of reasons why a kitten this age might vomit ranging from internal parasites (round worms) to viral/bacterial infections to a foreign body to food intolerance...just to name a few examples.
Since he's otherwise acting like a normal kitten should, the following would be my suggestions:
1. Discontinue the kitten milk. Some cats/kittens are lactose intolerant and will have gastrointestinal issues when given dairy products.
2. If he hasn't been wormed recently, purchase over the counter Pyrantal Paomate which is available at many pet/grain stores (at least that's the case here in the States) or online. This drug will kill roundworms, the most common internal parasite seen in kittens. I dose every two weeks for three doses. It will be safe to give even if he doesn't have parasites.
3. Consider a change in diet since some cats will have adverse reactions to the ingredients in their food...even at this young age. It's not common, but it can occur. Read the ingredient label and find something completely different.
Also cats who gorge or eat their food very rapidly are often triggered to vomit soon after they eat.
4. Ensure that there are no constipation issues since this condition can also trigger vomiting.
I hope this helps until you can have him seen but, again, my apologies for the delayed reply. Deb