Wow it's so interesting to read this is a common problem amongst tea drinkers. I have had bad nausea and sometimes vomiting after drinking tea, but only on an empty stomach. Throwing up is fairly recent, I've had these symptoms for only a year, but I used to get nauseous drinking ear grey so a few years ago I stopped. It was my favorite tea, so when the nausea got worse and worse I knew it was tea related and thought maybe I had bergamot poisoning lol. I can not drink earl grey anymore
The smell brings up that feeling.
So I was fine with other teas, I would drink whenever I felt like it. Until last year, then nausea started coming - I realized only when I had not eaten before hand. I go to school early and make iced tea the night before to drink in class for a caffein boost, sometimes I run out of the house sans breakfast with tea in hand, but this year I started to end up getting sick in the middle of class or driving to school.
Before drinking any tea, I just make sure I always have a snack, like a peice of bread even, to coat my stomach before drinking.