There is a big blood vessel in the area that can make the skin pulse. Maybe that is what you are seeing.
Yes, you could be feeling a pulse from the large artery that runs through your abdomen. Lots of women feel it as a heartbeat and think they are pregnant. Or they are feeling the beat of their baby's heart if they are pregnant when it is their own pumping. What about something gastrointestinal related? Any gas or bowel issues?
Sometimes this could be due to anxiety or IBS. I have had this before myself. It is a sort of spasm. Your doctor can prescribe an anti spasmodic if it gets too uncomfortable.