Check with Dr, first.
Sounds like too big too fast a drop.
5 to 4 is a 20% drop.
Suggest you go back to 5 until all normal for a week or more.
Then try the alternating method.
This will work out to a 4.5 dose over the time and only 10% drop.
5 day 1
4 day 2
5 day 3
4 day 4
If no pain, continue for 2 - 3 weeks