I Am Currently Living With Someone Whose 16 Year Old

I am currently living with someone whose 16 year old son has extreme changes in personality. One minute he is very compliant and apologetic about his behaviors and 20 minutes later he is extremely defiant and says completely outrageous things that are not related to anything. He believes that all authority, including police and government are out to get everyone. He has been caught numerous times getting high and believes everything he sees on youtube. He has been refusing to attend school and argues with his father non-stop about everything. He has already been diagnosed with ADHD and his mother may be bipolar. His behavior has been getting worse and worse during the last month. Is there anyway to get a psych evaluation that checks to see if there is a chemical imbalance?