I get small fluid filled blisters on mucus membranes from ALL antibiotics...starting deep in the throat/airways and working it's way out. I have never talked to anyone who has had a similar type reaction...until you. Is it affecting your breathing at all? My reactions will drop my O2 saturation from my normal of 98 down to as low as 91. It causes an awful sore throat as well.

My blisters take at least a week to reduce and feel better (longer to completely go away) after stopping the antibiotic.

I wonder if your PN and blister reaction is an autoimmune response. PN from autoimmune disease can cause rapid onset. An it's quite common for autoimmune disease to be trigger by an infection (viral or bacterial). My antibiotic reaction is thought to be related to my autoimmune disease, Sjogren's.