Canon SX50 HS half of a picture covered up by something in the lens?

I have a Canon SX50 HS and I was taking a timelapse with CHDK. I came back to the camera and it looked the last of the pictures had something blocking them. More than half picture looked like a blade of grass was in the way. I took out the memory card and the part that was blocked was still there.

Does anybody know what's happening? And how can I fix it?