very confused... any advice welcome!

so I tested positive on boxing day, and then negative the days following. my boyfriend said it can't of been a positive if all the others were negative :/ however I wasn't convinced as I was having all sorts of symptoms. my last period came early. however, on Monday night I got small amount of brown smudging, tiny amount. Tuesday is awoke with the darkest blood I had ever seen before. the blood was gone by the end of the day, however yesterday while I was out there was some blood same color, but seemed to have tiny blood bubbles/clots in it, it was seriously stretchy, and smelt really strongly of metal, I've never smelt that before. normally I can't smell anything! is it potentially a miscarriage? :/