ID this movie for me, please (aftermath of kids' rivalry gone horribly wrong)

I thought of a scene from this movie the other day, then couldn’t for the life of me think of what the movie was- and it’s been bothering me ever since.

Here’s what I remember:

Defintitely from the last 10 years, I think possibly from the last 5 years.

Played only in “Art House Cinemas”.

I knew and respected the Director before seeing the movie.
Don’t know if it was a Director with a decades long prestigious career, or if he had only done a few films prior. But I was already familiar with his work, his previous film(s) were critically well-received.

Basic plot that I remember:

[ul]
[li]Rival groups of kids- one group had a tree house in the woods.[/li][li]As the rivalry escalates, the tree house is set on fire.[/li][li]The kids who set the fire do not know that there is a kid / there are kids in the tree house.[/li][li]Possible there was a kid who died in the fire, definitely a kid who was badly burned- this kid thereafter wears a mask.[/li][li]Mask-wearing burned kid is brother to another kid in his group.[/li][li]Only one of the kids is a girl.[/li][li]One of the kids was fat but loses weight in the aftermath of the incident.[/li][/ul]

Most distinct memory:
The kid who was fat, is injured in a way that damages his sense of smell/taste.
Because he can no longer taste his favorite foods, eating is no longer a pleasure activity for him. He starts eating healthy (since he can also no longer taste the healthy foods that he previously disliked).
He starts to worry about his fat mother- who is a person who “eats her emotions”.
He locks her in the basement and feeds her only healthy foods.
While she is in the basement, there is a gas leak. He can not smell it, his mother smells it and has to break down the door to get out of the basement and save her son.

The actress who played the mother is one of those “that guy” actors who shows up a lot in minor roles. This may have been the great role of her career, she was excellent in it.

Anyone know the film?

Best guess: Twelve and Holding.

Looks good.

YES! Thank you!

Filling in the gaps:
I knew director Michael Cuesta from his previous film L.I.E. which was quite good- featuring a great performance by Brian Cox.

The actress who played the mother was Marcia DeBonis, as I said, one of those “That Guy” actresses who turns up in small roles in various projects. From her imdb page, I see that she is also a casting director. She was excellent in this film. Absolutely excellent. Certainly the role of her career (so far, anyway).

Larry Mudd, you say “looks good” so it sounds like you haven’t seen it. How were you able to ID it? You’ve got impressive Google-fu to ID an obscure film you’ve never seen.

Sorry to Spoil it for you, though an “I.D. This Film” thread will have Spoilers out of necessity.

I saw that in the theater and was ready to swoop in with the answer!

Oh, no worries for spoilers - I just put the title on my “want-to-see” list - I’m sure by the time I get around to it my poor brain will have omitted all the details.

If you have a few plot details you can usually find a movie by confining your searching to the imdb.

ie;
treehouse “gas leak” “sense of smell” site:imdb.com

…returned the plot keywords page as the top result.