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? My therapist thinks this was a drug run...but i wouldn't of gotten to this conclusion because of that. But her comments later on is that its 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's almost scary. 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.

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.