Confused ...miscarriage 5 weeks ago and....?

ok so i miscarried 5 weeks ago and did two ultrasounds. the first one i only started to bleed a little bit and when the ultrasound was done they said there was no sac or anything (i was 6 weeks along no need for dnc) the bleeding started and all tissue was expelled. I then did another ultrasound and confirmed that it was not ectopic and there was no tissue left in my uterus. Bleeding and cramps stopped and now im having a dull ache in the right side of my stomach what is this im not pregnant i know that for sure all my levels have gone down has anyone had this??