Side effects

Due to sleeplessness and hallucinations, my father's doctor has recently added Seroqul 25mg every night to the medications he is already taking (Zoloft 50mg day, and Aricept 10mg day).  Initially, my father was diagnosed with Alzhiemers disease.  His memory was fine at the time of diagnosis.  After that his original doctor also added Zoloft at 100mg per day and several other medications.    In November, he changed doctors, and she changed the Aricept to a patch that he applied daily.  When he made this change, he started having hallucinations and did not sleep.  So the doctor re-prescribed the aricept and added metformin.  After starting the metformin, he slept all day and would not sleep at night.  She took him off the metformin, but kept him on the Aricept.  The sleeplessness and hallucinations have remained unchanged. A few days ago, we took him back to the doctor about this, and she decided that he does not suffer from alzhimers but parkinson's diseas instead.  She added Sinemet 10-100 tabs, 3 times per day, and gave him Seroquel 25 mg to be taken nightly at bedtime.  We need to know what is causing the hallucinations and what our next step is.  My mother is a diabetic and her insulin has skyrocketed due to not getting any sleep.  Does my dad need to be detoxed?  He very sensitive to most medications, and we fear he is on too many meds for his body and his brain to handle.  He is 69.