When my DD6 starts acting cranky, I've realized what she really needs is a ginormous cuddle and some sympathy. There's no point in me lecturing her because she's well-aware of every single house rule - of course she only needs to hear things once and she'll remember them in fine detail!
(Which is why she's actually a delight 99% of the time.) It just makes her madder to be told things she already knows!
So I eventually figured out that a sit down on her bed and a nice bear-hug and some back-rubbing and soothing oh-dear-that's-no-good noises while she complains that she doesn't know why she's angry she just is, followed by some story-reading or other personal attention to fill up the old emotional tank actually fixes the problem better and faster than anything. Then she's back to her usual delightful rule-abiding self again. I figure we're all allowed a bad day without judgement every once in a while!
Good luck, I hope it all improves
