what is going on?

So it's been a week since I was supposed to start my period so initially I do what I always do, take a pregnancy test well it turned out negative. But since I got home tonight I've been having abdominal pain with vaginal bleeding and these muscus like blood clots that like body tissue almost. So I was researching my symptoms just to check out what might be going on. Well everything is telling me I'm having a miscarriage. But I've never found if I've been pregnant this whole time. What's going on?