9 Week old kitten not doing well

Question
I have a 9 week old kitten who is VERY tiny! He was the smallest out of the litter, and honestly is still 2 times smaller than the other kittens in the litter. Anyhow, when we first got him he was eating soft food ( I know for sure how old he is because he was born to my neighbors cat)... For the past couple of days he has been sleeping ALOT more than usual, yesterday he bacame very needy, wanting to be held all of the time... He ate normally yesterday and up until when he last ate today at 5pm. When it came time to feed him his dinner (still soft kitten food from the can) he sniffed at it and walked away. It was to late to run to the store to get some kitten supliment milk for him so I heated up some regular milk and got him to drink some of it, but he still wont eat. He's going to the bathroom and we have checked to see if he might have worms in it... we didnt see any, and I know that really doesnt mean anything. He seams to be breathing normally, but he is so sleepy and doesnt want to eat. Im terrified that when I go to sleep I am going to wake up to a kitten who has passed away. If it helps any to describe his size, hes honestly the size of a 3 week old kitten.

Answer
Amber,
Small kittens are small because something is not quite right with them.
These are the kind of kittens the mom's abandon knowing somehow they are not quite right.

We never recommend feeding cows milk at any time as it will cause some massive diarrhea that could get unstoppable. Better off just giving him some Karo syrup and water at that point.
You should give him that now and it might get his blood sugars back up enough to get him interested in food again.

Had another person send in a question just like yours and the same thing happened. He gave the kitten some karo and water and she was great in a few hours and back to eating and playing.

At the soon you can,and by that I mean today, I would strongly suggest you get him into the vets, get him wormed and vaccinated and TESTED for leukemia as well.
That is more important then the vaccinations at this point.

You need to find out why he is so small. Once you know if he is free of leukemia you can outline a plan with the doc on feeding him and getting him strong.

Pick up some Kitten Growth by Science Diet while you are there and you will have the best food out there to grow him big and strong.
They have it in canned and dry and once he is big enough I would feed him both.

Kitten chow has cows milk on it so stay away from that.
Kittens go downhill very quickly so please get him into the vet's today!
Please let me know how it goes and how he is doing.