...I am so sorry you have dealt with such a painful round of chemo cream. It's pretty safe to say that we all experience varied side effects, and I wouldn't be surprised if that nerve pain you described was due to the cream. It can be excruciating. I would certainly not rule out nerve pain as a side effect. You might try talking to your doctor and see what he/she thinks.
Generally speaking, I have been told to wait a much longer stretch between treatments. If your doctor has asked you to wait a month and retreat, and you feel you haven't quite recovered, you may want to address those concerns with your doctor. If I am told to treat an area, it's usually several months before I treat the same area again. For the most part, my treatments are a year apart. I completely understand the concern about it being too soon. The cream can really take a toll and leave you tender for a while.
I am including a couple of articles you might find handy as you move forward.
https://skincancer.net/life-with-skin-cancer/tips-for-efudex-users/
https://skincancer.net/life-with-skin-cancer/efudex-side-effects-tips/
Please keep us updated on what you and your doctor decide. Wishing you all the best! April, SkinCancer.net, Moderator