My 92 Year Old Mother Has Advanced Osteoporosis. She Is

My 92 year old mother has advanced osteoporosis. She is on various drugs including gabapentin. Doc prescribed a back patch for pain relief and after 3 days she is suffering continual severe itching and is now feeling faint. She has removed the patch after the doc said it was probably that causing the itching. How long will she have to wait before the itching stops. She hasn't slept for 2 nights. Thank you