Spotlight Massive (out of control at 100GB+) Macbook Pro, 500GB SSD, Yosemite 10.10.3

Is there a way to determine what folder(s) are giving Spotlight grief? Or some other recommendations to fix spotlight? 

Spotlight is killing my drive space at 100GB+. I can reset it, but after a day or so I'm right back to zero space free. The actual size jumps up and down, but trends to expand (+2,-1,+2, etc) until the drive is full.

Spotlight, as per 

 du -h -d 1 ./.Spotlight*


Yields:

110G  ./.Spotlight-V100/Store-V2

Resetting with 

 sudo mdutil -E /Volumes/[DriveName]


Starts over as expected frees up the 110GB, but after number of hours, it's back to a full HD.
It turns out that a driver (DisplayLink in this case) was generating gigs and gigs of rotating logs, and this was being indexed which was generating many more gigs. Finding the offending driver was the hard part. 

Remove driver (&amp; ditch the port replicator), re-index, all is well.