I have this nasty problem with my thump since last year. Not sure how it started, but I feel it started after some super glue touched the skin when I was in Costa Rico, but not sure. It became endless circle of problems. First blisters grow from deep in skin, which itches also, eventually opens, skins becomes yellow. Recently a doctor recommended me some creams, which worked well, but now the blisters growing again, maybe because I slowed down in using the cream. It only remains on my left thump.