What happened to my multiclip?

I cut an hour long sequence using a 3-clip multiclip. For some reason, when I went into the sequence the other day, my A camera has changed to a different clip. I don't even know which clip. It's from the correct project, but it's completely the wrong angle and timecode. I had previously collapsed my multiclip. I tried to reconnect the media, but FCP said the clip was both online and offline (?!?). I revealed it in the finder and tried to open the clip with quicktime player, and it has audio but no video. I recaptured the clips from my backup drive but now the clip name has changed.

Any suggestions on what I can do to get the correct angle back? Will I have to recut this one angle throughout the sequence? And does anyone have an idea of what happened so I can keep it from happening again?

Thanks!