Hi.. i have gone through the question and understand your concern for daughter. If she was in rehab then rehab people must have explained you about drug use or addiction as a brain disease and chances of relapse are high. According to change in her behaviour that you have mentioned, there is strong possibility that she has started using meth again. urine test for meth can give you clear idea if she is using it or not. In my clinic i usually prescribe minor tranquilliser for short duration, and focus more on psycho-therapeutic intervention to get details about reason of drug use, assessment of motivation, motivation enhancement techniques, identification of triggers, trigger management and relapse prevention strategies. I would suggest you to meet a psychiatrist for detailed psychological assessment and medicines if required.