Miscarriage

So i had some kind of light bleeding which was brown with a spot of blood in it which lasted about 2-3 days, about 8dpo which I thought was implantation bleeding. About 1 week later i started to bleed, really heavy, bright red with black stringy lumps in it (sorry,tmi!!) with a horrendous pain in my right side around my pelvis which made me cry at one point, my period was 3 weeks late so I thought i was pregnant but got a negative pregnancy test so I went to the doctors and they thought it might have been an ectopic pregnancy therefore wouldn't show up on the test so we're going to do some scans on me, however when i started bleeding they said i was alright because it was probably a period? It was an unusual period and very late! Could this have been a miscarriage? Thank you for your help in advance!