Based on the little information I know, at day five you are probably through the worst. In the first 17 hours, there is 50% decrease in serum fentanyl
concentrations. It's neither a quick or easy process.
Symptoms of Fentanyl withdrawal can include: anxiety, irritability, confusion, tremors, sweating, muscle aches, stuffy or runny nose, abdominal pain and rapid breathing
There is a lot of information on the net. Warm baths and exercise can be helpful.