Oh gosh, I've just read your post about her tooth - I don't know if you saw what I wrote earlier:
I woke thinking about your little girlie this morning and something popped into my head. One of my pups had a puppy tooth that was growing in the wrong place and he was a very feisty puppy (he's a lovely softy now) but he seemed to change overnight as his adult teeth came through. My point is, the puppy tooth that was in the wrong place was obviously causing him a lot of discomfort but the vet wanted to avoid operating on him as the adult tooth was likely to be in the right place.
It might be worth getting all her teeth checked as something like that (sudden onset of tooth pain) could be the reason why her behaviour deteriorated so rapidly. It's a long shot but worth ruling out 
Good luck
Hannah xxx
Dave had a lower K9 that was growing into the roof of his mouth and created a hole... by the time we discovered it, we decided to leave it to see how his adult tooth came through but in hindsight, his behaviour changed so dramatically when his adult teeth came through (in the right place) it must have really been bugging him - tooth pain is awful when you understand it so for a dog it must be 100 times worse.
I'm keeping everything crossed that you get a similar result for your girlie.. Dave was REALLY aggressive but he's not as energetic as some cockers so I guess that may have been why he wasn't quite so extreme as your case, but to highlight it, I did have to keep him separate from my 4 yr old son for the first 8 months.
Good luck for Friday!
Hannah xxx
