She was 18 she probably took something for cramps.
I don't want to put more weight on meds than might be appropriate, but Beth mentioned three things. Would she have included birth control pills, or cramp meds, or even eye drops for early onset of glaucoma in that list. As said, I might be dead wrong, but there is a possibility that the reference to meds meant that she wouldnt' leave them if she were running away.
I suspect her meds were important. I just wish I knew what they were.