Cat labor complications. Any advice?

It might be a undeveloped kitten that came out. Its strange that she had a kittens two days later. If she is still having signs of being in labor you should check the birth canal. This also might be a cut off part of the placenta of the kittens. Check for lumps in her stomach because this can be a huge clue to whether she has the body or another kitten inside her. If you can't feel lumps and if she isn't showing signs of labor all should be well. Cats have been having kittens for 1000's of years, so I'm sure if something was wrong she would show it. Hope the kitties have a happy life and good luck!:)