Burrow full of poop, what can I do?

[Milly_Hammy]

Thanks for the ideas!
The substrate layer inside Milou's house is 5 cm.
I've already put a bigger house made with a 30x15 cm box. for the past few days Milou has been pooping soft and sometimes very soft so it's sticking to his fur. The poop also has a strong smell, it wasn't like that. On Saturday I will go to another city to take Milou to the exotic animal vet.