Lightheadedness

I was sick for three days. Suffered from lightheadedness and stomach pain. I spent most of my time in bed because getting up makes me dizzy. I read a medical book regarding lightheadedness because i was afraid there is some underlying cause behind this and here is what i've read.

Lightheadedness is common when you have flu, a cold, or allergies. Vomiting, diarrhea, and fever can cause dehydration and lightheadedness. Other common causes of lightheadedness include side effects of medication, hyperventilation, stress, anxiety, drinking alcohol, or using illegal drugs. A more serious cause of lightheadedness is bleeding. If a person is bleeding internally, lightheadedness and fatigue may be the first noticeable symptoms of blood loss.

I didn't have all of those things mentioned above except for internal bleeding which i am not sure of. I was having this "girl thing" since friday, the time when my lightheadedness started. I just hope that is not the cause. Perhaps i am anemic. I have to seek medical advice soon.