What are clear blisters on the tongue?

I have these as well, and have been told it is an allergic reaction to something. I recently had a bad blood test, stating that my B-12 levels were extremely low. I began taking Sublingual Tablets and liquid form of vitamin B-12, which go under your tongue, to try to increase my levels before my next blood test. Apparently I am allergic to something in it. I now am taking benadryl, and it seems to be helping shrink them and help with the pain. My lips, tongue and the better part of the front inside of my mouth swelled and burned like nothing I have ever felt before. I lived with the constant feeling of just drinking something terribly hot and being scalded. The tip of my tongue felt like I was constantly getting paper cuts all over. I went to the Doctor, and was given a script for Magic Mouth Wash, and an antibiotic. 4 days later, I have clear blisters all over the center back of my tongue, going down the sides. So far, only the benedryl seems to be providing any relief.