I know exactly what you are going through. I just walked out on a job yesterday after a month of being there because I kept making mistakes that were continually pointed out to me. Mind you the me making mistakes happens all the time despite having earned a Master's degree. I get taken back to being in grade school its almost as if I'm being bullied at the jobs. Also the corrections make me feel pretty inept too. I always think to myself why didn't I catch that when I was preparing the work.