What Causes Blisters While On Hydrocodine?

in november i had sinus infection thats when it started. I was taking hydrocodine 500 for pain for fybromyalga. I thought the drug may be causing the blisters. after taking a antibotic they started to go away. They came back. stopped the hydrocodine went away. now there back. there on out side of nose not in nose. there full of puss and painful.