A very current topic: "I'm in a lot of pain" SPOILERS
Franny's character frequently utters "I'm in a lot of pain." And I believe him, except it's not physical (as one can see when he's sitting in the ER after he injures his hand).
Franny has never received psychological help for the car accident in which his friends were killed. Another poster on this board argued that Franny caused it, but I didn't see it that way. Even if he did, it was an accident, and either way Franny has survivor's guilt which h as never been addressed psychologically.
Many drug addicts probably have unaddressed psychological pain, which manifests itself into a drug addiction of some type (Franny said he's "not a drug addict" because he was addicted to prescription drugs).
Let's hope he gets his much needed psychological help in rehab.