What could it be? It's pulling at my lower abdomen since last evening …

What could it be? It's pulling at my lower abdomen since last evening and this morning. Sometimes it pricks, my stomach is hard, I can't find a comfortable position. Yesterday in the afternoon I put on boots with heels, I can't say that I walked much, but it was difficult and uncomfortable to walk, came home tired and after some time it started. I think it might affect me or not? Could it be a spasm or muscles pulling? Probably around lunchtime I will go see a doctor.