Pain/burns on Face After Facial?

3 days ago, I had 4th microderm facial which included a lactic acid mask. The first three times, my skin looked perect afterwards. 4th time- soon as the lady put on the lactic mask, my skin burned horribly! She removed it but it was too late. It actually looks like a burn more than anything else. It's painful and burns and it's day three still. Smiling hurts. Same woman/ same products were used all times. Haven't changed my diet, medications, lotions etc. What happened?