Make Me Forget// Spencer Reid's Daughter

"Well, you look like yourself
But you're somebody else
Only it ain't on the surface
Well, you talk like yourself
No, I hear someone else, though
Now you're making me nervous.." You're Somebody Else by Flora Cash.
--------------

Spencer's daughter, Angelina Reid, starts acting weird after an incident involving three boys. She doesn't tell her father, Dr. Spencer Reid of the FBI about this incident, and suddenly changes into a whole other person. He begins to worry, but Angelina won't let him in. One month after the incident, Angelina finds something in the bathroom that could make her pain go away... a small bottle of clear liquid. Three months later, Spencer starts to see the signs. He knew those signs. He lived those signs.

Was Angelina doing drugs? And if she was, then why?