So..Ive got this problem..

I started modeling this today and now I'm stuck. I started modeling the back leg out of a subdiv cube and then attached it to the body connecting the vertices. Then I combined the two, and merged the vertices. I converted it to a polygon and went to clean up the polygons and clicked 'nonmanifold geometry' like I did with the front leg, so I could convert it back to a subdiv. When I converted it back all of a sudden I see this. I have no idea what happened and how to fix it. Has someone had this happen before? Can you help me please? I'd like to get back to working on this.

Thanks!