I'm confused. A bit long sorry.

Hey could I get some advice? I took a test 2/3 weeks ago it was positive then a couple of days later I was spotting then I had one clot wasn't massive but I still rang my local hospital to get checked out seeming as I had a bfp so I went to the hospital that afternoon told her everything and she made me test again witch came back negative! So she told me I had MC I'm not sure if I'm right but aren't they meant to take blood to confirm a mc? Took a test today its negative I've been feeling awfully sick last week and I have this gut witch everyone is noticing and bad cramp in my legs in the middle of the night. I'm very confused.