Agreed - Go and get the blood tests, it's not a waste of time and if they come back fine then you can rule out some nasty stuff. As it happened two hours after donating blood I'd suggest that it isn't anything serious, especially as it occured in the toilets.. ...you see, having a poo, and to a lesser extent having a wee, lowers your blood pressure and slows your heart rate. With less blood in your system than normal this may have been enough to cause you to faint. When people faint they sometimes jerk around, and this can look like a fit to someone who isn't used to these things. Also adults can have one fit 'out of the blue' and it doesn't mean anything. So my advice is to check it out but, given the circumstances, not to worry too much.