Odd blood-clot? Help please

So last night at around 2 am I had this really bad cramp that woke me up from a dead sleep it was so bad. It went away after ten minutes and then I went back to sleep. 
Then when I got up this morning and went to the bathroom there was this thing in my underwear that I thought was a blood clot but it's not. It's over three inches long and an inch wide. It's only got blood on the end and most of it is pink and white. 
It feels like flesh and skin, it cannot be pulled a part and broken, and smells really odd, (pardon the TMI) but it doesn't smell like usual period stuff. I'm very concerned, does anyone know what this could be?