i would get my daughter to a pediatrician and let them sort it out.
first, i think you would have noticed she was an addict's baby when she was born, if you seen her then. that is when the majority of issues show.
since she was adopted you know nothing of her family's mental health history. it could be major or she may be having difficulty in some environment of her life that you are unaware of. good luck
There is no genetic test to check for addiction and after 7 years, there will be no drugs in her system or body. Every 7 years, every cell in the body is replaced by new cells. Pediatrician is a good idea, counseling wouldn't hurt either. I wish I had gone to counseling at that age, I may have avoided my own addiction. I swore I would never be like dad, but I was never taught better coping skills. IMO, helping her gain skills to deal with mental,emotional/ohysical/spiritual problems would be beneficial no matter what the cause of her issues.
I would take her to your pediatrician and tell him/her what is going on. They will be able to direct you in the right direction. Good Luck~