Thank you for your question.
Fentanyl is 50 to 100 times stronger than morphine and is not appropriate other than for extreme pain that does not respond to other medications.
The official NIH information states:
1 INDICATIONS AND USAGE
Fentanyl transdermal system is indicated for the management of pain in opioid-tolerant patients, severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.
Patients considered opioid-tolerant are those who are taking, for one week or longer, at least 60 mg of morphine daily, or at least 30 mg of oral oxycodone daily, or at least 8 mg of oral hydromorphone daily, or an equianalgesic dose of another opioid.
So it may not have been appropriate to prescribe it but I cannot tell without more information.
The Experts here cannot represent you, but you can get a free consultation from some of the medical malpractice attorneys listed by location here.
Please follow up on this with a local attorney.
I hope this information is helpful.