Is a stong opiod pain medication. Is is usually one of the drugs used in surgery as part of the anesthesia. It is usually used when some of the opiods (like oxycontin) aren't helping (because fentanyl is highly addictive). In patch form, it can be worn for 72 hours. The patch comes in several strengths ranging from 25-100micograms/hr. Some side effects include high/low blood pressure, GI upset, dry mouth, headache, and, difficulty with urination.
It sounds like you are having a terrible time right now. It is my prayer that things will get better for you soon.