I sent a private message to J-9, who is the health expert on this site, asking her to address your issue. I am sure that she will answer your question soon.
Just from my own experience, I developed an intolerance to caffeine. Used to drink beverages that contained a lot of it. After awhile, having so much caffeine in my system actually made me tired.
Because of how my body has changed, I have no tolerance for caffeine anymore. Can't ingest it. Makes my heart do things as well as making me very nervous. Plus, it does not do good things for your liver.