caffeine sensitivity?

A year ago, I had an anaphylactic reaction to a food (I'm severely allergic to peanuts/nuts/treenuts). I used to drink coffee ALL THE TIME IN EXCESSIVE AMOUNTS with zero side effects, only the positive side effects. I've never EVER experienced anxiety in my life, and then suddenly, after that allergic reaction, caffeine was never the same. I started getting really paranoid and anxious from drinking a small amount, and I can't even develop a tolerance to it anymore because I start feeling like I'm crazy. I have heard of people becoming randomly sensitive to caffeine as well and I'm curious as to why this would happen. The only thing I can think of is that I had drank 6 cups of coffee the day I had that reaction, and maybe my body now recognizes caffeine as a threat. And when I mean excessive amounts, I'm talking I drank at least a full 12 cup pot of coffee a day, sometimes more, and never had problems.