I drank a cup of milk tea at 6pm and my heart felt like it has been racing ever since. I'm having trouble sleeping. I'm a teenage girl on the small side, if that matters? I've had this problem once before when I drank a cup of coffee, but up until then, I could drink coffee, an energy drink, or tea with no problem. Is there anything that could happen to trigger this change in the way I respond to caffeine?