She cares, you're just overreacting, maybe she didn't go to buy medicine spontaneously because she thought you were joking and she was in a bad mood for jokes so she just ignores you, and you didn't tell her it wasn't a joke or ask her to help buy the medicine, if you don't communicate, nothing works, have some transparency, she's your close friend after all, if it's someone you don't know as well, it's fine, but this is your friend for many years, you just have to talk to her about it.
D
