Hello -I have been diagnosed with quite severe Otitis externa and now that I am on the correct ear drops I am progressing well, no longer requiring pain killers. A check on progress today by an ENT has revealed a large blood blister. I will continue on drops and return in a week so they can check progress again and hopefully be able to see my eardrum which is blocked from view by the blister. I ve not had Otitis externa before and wonder if I should be worried about an underlying cause? 44 yr old female, NZ.