My little dog is a chorkie and is 10 months old. We have had him from 8 weeks and he is well trained.
He is always keep in doors.
This past week he has been pooing all over the house... Usually at night. When I get up in 6 hours time he has maybe did 10 poos. We put him out before bed and he goes.

How can he poo this amount when he eats very little?
Also why has this just started?
What can we do?

He is not sick as he is very lively etc.

What do you feed?

Grocery brand foods are full of fillers and dogs will produce more poop even though you're not feeding a lot.

Find a good quality puppy food such as Wellness, Nutro, Blue Buffalo or Natural Balance are good foods to investigate.

Feeding a good quality food, from puppy hood into senior, will reduce the amount of stool produced, make your dog smell better as far as body odor and breath and also give your dog a beautiful coat.

Great advice so far. That little fellow should be crated until this is resolved. High quality food, lots of exercise and feed no later than 6:00 PM on a very regular schedule. They only can poo what they eat. If he eats 2 cups a day that's all he should be able to poo. If he is putting out more than that then he has an intake you are not aware of. When I look at a new dog food I pass the mainly grain brands and go for one where a meat is the first ingredient