Working just fine this morning - now itunes wont properly backup my jailbroken phone

[andyd]

not sure what's up. it takes forever for the process to begin and to get to the end. but at the end, the backup app crashes. I have no idea what's causing it or how to fix it

EDIT: Is there any way for me to figure out what is being backed up? I see that it's trying to back up over 12 mbs even though prior backups are just around 612kb. The only thing I've done since Sunday was install the updated version of SwirlyMMS but I ended up deleting that. I need to extract that mdbackup to see what's taking up all the space