Hi, the same thing happened to me tonight. I am very sensitive to stimulants, I've had several caffeine induced panic attacks in the past. I have been trying to eliminate caffeine completely, drinking only decaf drinks. I can tell you though that even decaf drinks have caffeine, I read a study saying that only 1 in 20 decaf products actually have 0 caffeine. I also felt hyper and had a panic attack after drinking decaf coffee at home once. Tonight I had 4 bags worth of green tea over the course of 4 hours and started having a classic panic attack soon afterwards. I would bet those decaf teas you're drinking aren't actually caffeine free and that your body is reacting to it.
My view is that green tea may have anti-oxidants that are good for you, but so do many vegetables and they certainly have 0 caffeine. I'm staying away from all teas and coffees, decaf or not from now on. It's just not worth the risk of another panic attack for me. I'll get my anti-oxidants from broccoli and other veggies.