One cat acting very strange, vicious attacks repeatedly?

I have two siamese cats about 3 years old, a brother and sister. I got them a few years ago and they were inseparable until 3 days ago, when I was forced to separate them because the girl is attacking the brother all of a sudden. For the last 72 hours, all she does is stalk him if they are in the same room or wait to attack outside the door. She hardly eats. I'm worried because she scratched him in the eye and he was bleeding, also little chunks of her fur with skin are all over the kitchen.

There's been so many things happen newly to them in the last week, so I have no clue what caused it and my vet just doesn't care at all about them, even after spending hundreds of $$.

-minor fracture on a 40 watt cfl spiral bulb after I dropped the lamp….took me 30 minutes to decide to throw it out bc mercury gas could be leaking? Three days after (today) I smelled her coat and felt a little burning sensation on my lips….
- Catnip containing 4 herbs, including valerian, honeysuckle, and catmint given 5 days ago?
- First time cat door installed 5 days ago inside house, girl very scared of it and hasn't learned?
- Girl had a runny eye 7 days ago, so took to vet and got a shot of antibiotics, take home clovamox for 1 week, and vet shaved her neck to take a blood sample. No bad results, but 3 days later I found a small fresh blood spot on my bed.
- Basically the only thing that happened the same day before the attacks started at midnight was the bleeding and the cfl bulb fracture.

Any ideas?