Thing is, now is not the time to lay down the law and put a new routine in place. The time for that was years ago, or after mocks.
We have a deal in this house that if it's around mocks or exams, we cut the teens some slack, so expect less help around the house, not make a fuss about rooms etc.
After mocks or exams are over, good time to re-establish what needs doing. I've just done that this week (after mocks), and my kitchen was sparkling clean! It's a good time to sort clothes, clean rooms and get it all going again.
For now, I'd give her a hug and say- sorry, but it was smelling in your room. I'm going to remove the plates and hang up towels, if you could do that, it would be appreciated. Otherwise, we'll get through this week.
For more house-proud people, this might not be ok, but now isn't the time to have a go about this. I also let my house go to rack and ruin when I'm busy at work, then have a day off and blitz it and I wouldn't want to be told off when rather stressed either.