Hello. I Been On Depo For About Five Years Had

Hello. I been on depo for about five years had my last depo shot in January. I haven't had a period since. My periods were always regular and usually come back on soon as I stop taking depo. For about two months now ive been feeling nauseas, having pains in my stomach. Yesterday I started feeling movements in my stomach I took a pregnancy test today but it came up negative do you know what it could be?