My aunt thinks there are electrically charged snakes crawling on her skin. Any ideas?

My Aunt is 76 and has MS. She is wheelchair bound and has been taking 7.5 mg oxycodone multiple times a day for many years. She is clear headed most of the time but her doctor and I have noticed the onset of dementia. She recently has been having a problem with snakes crawling over her body. They are not always in the shapes of snakes but most of the time they are. She cannot see them, hear them, they don't bite her but they have a sort of magnetic or electrical charge to them. She has not been shocked by them but says that she almost was once. They really bug her. She spends the whole day trying to pull them off of her and putting them into a folded up t-shirt on her lap. When the t-shirt gets full she has me take it outside to shake them out and then wash then put it in the washing machine. She wishes they would go away but they seem to be getting worse. Her doctor sent her to a psychiatrist who has tried 3 different medicines but non of them work. Her neurologist has done a brain scan and found no differences from her scan last year. My aunt now is convinced that these snakes are something evil and wants to have an exorcism done. I am not sure what my next step is when that does not work. Any ideas?