I am unclear as to whether or not you are pregnant, but if you are, this is quite normal. Some of the things that helped me were ginger, lemon squeezed into water, and keeping something in my tummy all the time, even if just a cracker to nibble on. If you are not pregnant, it might be best to see your Dr. Good luck.
It could be any number of things. If it continues much longer I suggest you see your dr for a diagnosis. In the mean time try eating the brat diet ( bananas, rice, applesauce, and toast) as this often helps people who have an unsettled stomach.
it just sounds like early pregnancy. try eating fruit to combat peckishness and maybe settle your stomach