You were not kidding, half an egg white is not a lot of food...
I rarely have problems with my stomach, I attribute that to my upbringing in a "lots of cream, butter and desserts"-type of way that my mother has done. I mean, I have seen people come into our house for dinner and be very sick the next day, or shortly after dinner and us being in great shape...
in any case, I hope you get better soon.. very soon.