What Causes Movement In Lower Abdomen While HPT Is Negative?

For the past 3 days I have been feeling a bubbly or moving feeling in my lower right abdomen area. I have taken 2 pregnancy tests and they both come up negative. I have 2 kids already and there are no other signs of being pregnant. However the feeling im experiencing is like a baby moving. I can even put my hand on it and feel it move. I have no discomfort.. just a constant move. I also show no signs of being gassy or indigestion.