Celebrating too early?

So I went out for dinner tonight with a few friends from work.  It was really nice to celebrate my BFP.  But after dinner I felt really full, like I'd eaten too much, but I hadn't.  Then I got a mild menstral-like cramp that would not go away.  At around 10 pm I went to the bathroom and felt a lot of pressure and bloating.  There was a small mass of tissue in the toilet.


Did I just have a miscarriage?  Is this a 'chemical pregnancy'?  Did I do something wrong?

Feeling very alone right now.