I have been feeling really sad, recently lost my 23 year old niece.
Our family has been really sad. We recently lost our 23 year old niece.
user
Thats terrible.
assistant
She had been sick for a bit.  She had something called encephalitis.
user
I have heard of that. 
assistant
It is like and infection in the brain.  It came on pretty sudden though.
user
I'm so sorry for your loss.
assistant