I Have Been Using Fluorouracil To Remove Basal Cell Caracinoma

I have been using fluorouracil to remove basal cell caracinoma on my face. I had used it on my arms and legs, with discomfort, but it worked. My arms have healed and my legs are on the way. HOWEVER, on my face it's a different story! I have had a good deal of dental work done and a "canker" sore is on my lip. I saw a doctor and ask what she would recommend ( I can't wear my new extended partial) because it hurts too much, so was trying to clean up the sore before returning to the dentist. Well this morning I decided to use the neosporin on the spots on my face. All seemed OK until an itch started on my arm! I'm trying to find the best avenue of getting back on track! Any suggestions?