Chemical or not ?

I can't be certain if I had a chemical

pregnancy or did we just not conceive at all and I got my period as normal.

I had faint line on clearblue test at the evening 3 days ago it was a clear positive.. in the morning around 9 am I tested with another test and it was negative..

Later that day I started having stabbing pains ( different pain to my period ) and At first I had pink discharge when I wiped and then brown discharge with mucus ( sorry TMI ) only a little bit all day - I actually thought it was implantation bleed at first I had just that all day.. but next morning woken up by a period - now my periods are usually heavy and painful but one ibuprofen pill sorts it out - with this one Its kind of much lighter than my usual and it hurts so much I can barely walk.. I took 10 strong painkillers today and pain just won't settle.. it looks like normal period with a bit of brown discharge but the pain is insane.. could it be a chemical or unlikely ? Xx