And it's driving me completely crazy because I have no idea why.

Her and I are basically thick as thieves, we hang out every day and I am her only close friend that lives here (the rest are away for school right now in other cities). But for the last 3 days, she's been totally ignoring my texts and calls and I'm starting to freak out and wonder what I did wrong. 

She has quite severe depression, and she does have days where she will ignore everyone, but I can't help but think it's a problem with me. I know she's still doing stuff on social media.  

This is a really toxic combo because I have BPD, and so my biggest trigger is being ignored or any signs of abandonment. And as a person with depression, she's very inclined to go through periods where she withdraws from people. I want to respect her mental health and her needs but managing my own triggers here has proven really tough. 