What Causes Spotting Without Being On Menstruation?

My question is regards to my wife. Yesterday she had some cramping (somewhat painful she said), she went to the bathroom and her underwear had blood in them. Today she didnt cramp but when she went to the bathroom she had a clot. She is not on her period, and its not soon. Its been about a week and a half since her last period. She cannot be pregnant because she had our last daughter in January and she was fixed. lol. Not sure what this could be? Should we be worried/