First of all not too sure where to put this, so mods feel free to move to a more appropriate place.

Just wondering for those who have a mental illness what lead to your diagnosis/getting you help.

I have a friend (who I also used to live with) who has considerably declined in social function (I guess in the last 4-5 months) and am starting consider she may be showing early signs of a mental illness due to the drastic change in her behaviour. She has become very paranoid towards her housemates (is now camping in the backyard, as she thinks they are constantly disrupting her - they aren't), will leave rooms when certain people enter, has become very passive aggressive and is currently driving all of her friends away due to her behaviour.

Does sound like early symptoms? She has become a completely different person to who she used to be. How can we get her help?