I can't stand the smell anymore!! How to get my flatmat to be more clean!

So I'm currently living with my partner and we've allowed his brother who's 30 to stay with us till he finds a house. He's quite a bit older than me so I thought he'd act like an adult you know. But no, he is so bad at cleaning after himself and my god everything he owns just smells. It's like there's this aurora around his things and you don't even have to be close in order to smell it.

We have spoken to him several times, especially about the dishes because we share kitchen stuff and we are sick of releasing things. Nothing changed. I have messaged his mum which did lead up to him finally cleaning his room after like 7 months. I think I saw him empty 4 bin bags and it is a small room so no clue how it fit in there. It's been 2 months since that was cleaned and the smell has gotten worse.

He leaves his coat on the kitchen door and I just smell it whenever I'm in there I can smell him leaving his room when my own door is shut. He leaves a trail aswell and it's just unbearable when he's really smelling bad.

He washed his towel a week ago after like 7 months of not washing it (he keeps it in the shared bathroom) and there's been mold on the door that I keep cleaning off but he doesn't seem to care that his towel smells and is like green.

I am honestly disgusted by this man. He seems OK mentally. He's very kind and sweet but he just doesn't know how to keep clean or be aware of his smell. Apparently he's been like this all his life and used to even pee in bottles in his room when he lived back at home.

We don't want to kick him out because we are away from his parents and he's helping with rent but honestly I am struggling to live with the smell and untidiness.

I don't know what to doo.