SOMETHING IS WRONG WITH ME...

Cecilia
Hi all! About 3 weeks ago I got a BFP (check out my post) and I knew it was way to early know for sure so I waited a few more days. Few days went by and I got a BFN in a few different test. I have been feeling a little off lately, very nauseous, vomiting, dizzy spells, tender breast, all pointing out that I was pregnant... about an hour I started to feel cramps, extremely strong cramps and very sharp back pain, I go to the bathroom and well there it is, blood, not reddish blood but brownish/reddish mixture. I start wiping and as I wipe more it started to get redder, mind you I am still in excruciating pain, very similar to labor pain. 
Idk what happened, I was so sure, so so sure. I feel horrible, so disilicional and just so sad. 
Anybody has experience this? Did I have a chemical pregnancy? A miscarriage?