TLDR: friend recently became depressed. what resources do i suggest? what steps can make her life easier? would therapy be helpful, even if she can't pinpoint a specific issue?

i've been depressed my whole life as well as having bipolar 1. i know the steps i took to get better, a lot of which was dealing with past trauma and seeing a therapist, as well as medicating. 

my roommate, who is one of the most determined people i know, has been struggling recently. she's premed and very intelligent, but recently had been skipping classes and sleeping a bunch. she came to us and said she thinks somethings wrong, and she was going to her family doctor (who ran a blood test and told her it was probably a potassium deficiency that was causing the depression, even tho her levels were within the normal range.)

i've told her to go to the student health center on campus, as they are much more understanding of young peoples struggles and open to treatment for depression. i've had a really good experience with them. i'm struggling beyond that. 

what do you do when someone develops depression later in life? is therapy something i should suggest? or is medicating the first step? i feel out of my depth. i want to help her and make things easier but i just don't know what to do.