Worried about my friend.

I'm new to the world of drugs. My friend used to do drugs she admitted but said she wasn't anymore. One day she made a random trip 3 hours away and when I asked her what was going on, I had to play 20 questions and took forever to get an answer. Finally said she went to look at a school but it was June and all school were closed, if that were the case why make me play 20 questions and be all secretive about it? Why not just say that right away? My therapist thinks this was a drug run...but i wouldn't of gotten to this conclusion because of that. But her comments weeks later is that is where my friends are that make the meth....

I'm worried she's on the meth again because things were good then she got weird and distant and mood swings, crazy, it was incredibly scary. She is 100 pounds and me at 210, yet these mood swings would scare even me. Had heart problems and afraid she will again, had another health scare and blowing up my phone about it. Asked a few days later how she was and blew up on my saying I want to know everything and don't need to...I was only asking how she was doing after her health scare. Seems like the mood swings and such are pry because of drugs. Why be defensive and be so secretive, and why would someone ever get mad about someone caring how they are doing?

Can someone with experience in this weigh in? I don't want her to die and don't know how to help her, she blocked me on everything after asking her how she's doing. Even if it's not meth I'm guessing it must be something. Please verify if you think it drugs, why you think that, and what I can do? Plan on sending some information in a packet in the mail anomalously, making sure she can't trace it back to me. Is this a good idea, figured it can't hurt, any other ideas that might help?