It rarely happens with green tea, or expensive teas (actual teas, I don't think it happens with herbals). But it DEFINITELY happens anytime I consume even a tiny amount of black tea (specifically Lipton or cheaper brands). I know the tannins and acid cause problems, but think about it from an alcoholic point of view. Do you get a worse headache from over-consuming the same amount of  premium vodka or cheap crappy Skol vodka? Do you get a worse headache from cheap red wine that contains excess sulfates  or wine that has been decanted. It's possible one is worse.

Maybe the cheaper the black tea, the more garbage that's in it and the worse stomach reaction. Still, it happens with most, just more intense problems when it's cheaper quality.

Don't drink tea without food, sip it slow, or add stuff too it (milk or lemonade) and don't drink it too fast or too concentrated unless you have milk or bread on hand to stop nausea.