There must be something in the air.
My fifteen year old did the exactly the same thing last weekend. I allow her to drink (very small amounts) at parties but not get drunk. She didn't take any drink to the party she went to last weekend because she said she was ill and was only attending for an hour to be polite.
She got so smashed she didn't dare come home. Fortunately, her fifteen year old boyfriend was mature enough to realise she needed help and called her grandad to come and collect her after she threatened to runaway. I was very impressed with him, not so much with her.
She fell through the door sobbing, begging me to take her 'home' to her father, pleading with me and her sister to go back and live with him, stating she missed him, she missed all the cooked breakfasts he used to make her and the tele they would watch on a Sunday morning while they ate said breakfasts. Me and her sister were baffled. We had no memory of him cooking breakfasts.
I woke her up at 10am the next day with a fry-up and forced her to watch The History of Football
. We had a good chat, she has no clue why she said she what she did. She doesn't like her dad, she does remember the breakfasts but isn't sure who cooked them (it was me, they happened rarely) but she remembers the abuse more and would rather live in a field in a tent than move back in with him.
She does have depression and anxiety, so that might be something to look into, OP. She also doesn't respond well to change and we've just moved. She thinks initially when she was talking about 'the old house' she meant our previous house. That is where she planned on running away to, she believes. It was only when I told her they'd decorated it and wasn't the same anymore she decided her dad's was the next best thing.