Sorry to hear about your Dad what meds is he taking on a night ? it seems to me that if they are making the situation worse I would certainly question if they are the correct meds for him.
I also have PD and in the early days was subscribed Quetiapin Aurobindo (25 mg) to help me sleep they worked for me, however we are all different and what worked for me may not work for your dad.
But I would certainly take this up with his Neurologist.
keep your chin up there is always a solution just a case of persevering.