What Causes Fluttering Sensation In Abdomen Despite Having High BP And Cholesterol?

Hi,I m a 61 year old women in pretty good health. I m being treated for high blood pressure and high cholesterol. I m fairly thin. I ve recently started to have a visible fluttering in my upper left abdomen. It s not constant but it is frequent. You can actually see the area pulsing. Any ideas what this could be?