Need help! Pregnancy after Miscarriage

According to my app which I know isnt always going to be completely accurate, says I'm 4 DPO and 10 days until next period. The past 2 nights I've been finding it really hard to get comfortable and fall asleep, have had a slight headache throughout the passed 2 days, body has also ached (mostly my torso but really bad in my lower back) have had some cramping here and there the past week. I'm not sure a pregnancy test would show this early but mine are sure enough negative, what could be going on?!