Think you're right.
She's probably got a 'Makosi pregnancy'
It's very fishy, she didn't seem ill or in pain. She is apparently having tests in hospital over the next few days. With a bit of luck they may find some kind of personality there if they look hard enough.
I think she's pregnant by her boyfriend outside the house. She admitted she had sex with him a week before going in. The timing would be about right for her to start feeling ill. And she's apparently on an IV, which she might be if she's weak and dehydrated.
I was wondering the same. Even the housemates don't know. She isn't coming back either. Somethings off about the situation.
What REALLY happened??