Too much coffee

I have been working away a lot in coffee shops recently. As a side effect this means I have been drinking more coffee than usual.

I have been peeing about 12 times a minute and yesterday after 3 large iced coffees I got all jittery and had a hard time concentrating.

Too much caffeine really is not good for me and I am not used to handling it like most people as I never used to drink coffee.

Do you have a reaction to caffeine?