Hi,
I did nofap for about a year or so. It was very useful, and would recommend everybody to try it for at least three months or so, especially if you have addiction issues. It taught me a lot about sexuality that nobody would have been able to explain to me.
Anyway, it is very well known that nofap can cause "ups" and "downs". Periods where one feels strong urges are common. They will go away, usually within a few days or so.
Therefore, I'd recommend to keep going. Don't give in to any urges, and try to ignore any pain that you think might be related.
And re-evaluate after some time (people say that nofap requires at least three months to be effective, which I think is about right).
Good luck!