She had it because she was going to give it to her teacher who was saying she's crazy.@Velsy and @Invader_Retro the things are real, but she doesn't knows what they are. She explicitly says that she is not doing the drug, and she sees them normally anyway.
as for why does she even has that drug or how it's even made? who knows for now, maybe she got them from someone when she found out it could be used to see the things, to make sure that she was not crazy and that they were real, but for now we kinda just have to wait the next chapters.
Are you retarded ?I sitll really confused why its a drug.. does that mean shes taking the drug all the time ? Stop dopping then. In that case, its all just hallucinations from the drugs. Kinda like when you eat shrooms. You see wierd shit.