Re: not sure if it's bipolar?
As much as I know you really want to help your friend, there is not a lot you can do except to advise your friend to seek the diagnosis of a professional. Unless and until you and your friend are sure what is wrong, neither of you are in a position to do research or help in any way because you don't know with what it is you're supposed to be helping.
I know this sounds like a copout of an answer, but unless you are a professional, she needs to see one; and the sooner the better. Once she is correctly diagnosed and medicated, she will hopefully feel better and will be more equipped to ask you for any help she needs.
I pray that you talk her or him into seeing someone. You both will be better off for it. And because your friend may not be able to see it, thank you for being so open to helping.