Confused. Can anyone help

Hiya, so basically I had a miscarrage about 3 weeks ago. My levels were going down as expected and I took pregnancy tests and it's back to not pregnant again. I've been taking ovulation tests to see if I can track it again but they've all come out negative. My app says I'm due my period tomorrow and I've been getting pains, particularly in my right hand side and my boobs are sore. I took an ovulation strip and allthough it's negative, it's all darker then it was the previous day. Any clue what's happening?