change in bowel movements - pretty anxious

I'm a 24-year old female that seems to obsess about her health and always assumes the worst! About two weeks ago, I had a bout with the stomach flu - typical nausea, vomiting, chills, etc.. I admit that I have what I've been calling a "nervous stomach" - seems that stress goes right to my tummy. Since the other week, I really haven't been in the mood for my usual Raisin Bran breakfast - I'm now eating toast, fruit, and sometime oatmeal. I've also started eating lots of salads (at lunch usually a big one with lettuce, carrots, cukes, mushrooms and croutons with oil and vinegar dressing and sometimes another one at dinner) as I had noticed that my eating habits had gone downhill! My last two bowel movements (about 2 days apart) have been more greenish in color - the consistency and frequency hasn't changed, just the color. I'm freaked out - should I really be worrying? Again, I tend to worry all the time about my health, even though I have never had any real health problems other than the anxiety.