One of the most common causes of discomfort and even bowel irregularities in the lower abdomen is irritable bowel syndrome.
You might want to research that and see if it sounds like you. IBS is a benign although very uncomfortable condition. I have it and control it with diet (simply do not eat foods that I know irritate it) and trying to keep stress levels down. It might help to keep a diary of what time of day on a certain day you eat or drink something, when you get intensely emotional about something, and see if anything matches up with your symptoms.
I myself often know I am going to be hurting in the bowel area later if I start to feel an unexplained "sinking" feeling in the pit of my stomach after I have eaten something I am not used to.
If you do have it, there are also prescription medications you can take for it.