The pain is most likely due to constipation.
You haven't mentioned if you are a male or a female and also if the pain is in the right side of the lower abdomen or the left side. By far, the most common cause of abdominal pain is constipation
The cause of lower abdomen pain, if you are a female can also is due to irregular menstrual cycles with loss of excessive blood. This can lead to anemia and also to light headedness, which you are experiencing.
If you are a guy it is very likely to be due to constipation
I would recommend the following things-
1) Start the use of stool softeners to improve your symptoms. Use Colace or Diocto that is available over-the-counter. It may cause a few side effects like abdominal cramps or flatulence.
2) Increase the amount of fluid intake as it will not only improve the symptoms of constipation but also help to improve the light headedness.
3) Get a Hemoglobin level check up at the nearest lab. It is the most common cause of light headedness in both males and females.
4) Maintain a healthy bowel routine. Maintenance of a routine helps body adapt to the evacuation of bowels and hence decreases the chances of constipation.