The sore could be causing it, especially if you have been diagnosed with Herpes simplex. The area where the blister is is very sensitive and will radiate, making it seem as if you having pain there but it just stemming from your nose. You should see your doc so that you can get the proper tests and diagnosis. If it is what I said it is, there are medications and creams that make it easier to deal with when having an outbreak.
A viral infection can cause this.
If this is NOT subsiding, please consult your physician.