Stuck - need help schedule/enrollment update relationship?

Help!  My brain is stuck.

Here's the situation.  I'm using filemaker to track/schedule/budget classes for a college department.  I've got tables for faculty, classes, class sections, etc.

So far, so good.

Once the schedule is set, say for the spring semester, I'm getting daily updates on enrollments - sometimes changing room assignments or faculty, etc.

So for the spring semester I'll have multiple updates.  Most of the info is identical update to update (i.e. class number doesn't change, enrollment cap, blah, blah) but other info is changing.

Here's where I'm stuck.

Ideally, I'd like to track those changes update to update and either highlight the changed info or calculate the change (i.e. enrollment in class xx went up by +2 students, etc.)

I get that I'll have to add a filter/button that sorts by the latest update (i.e Spring Semester, Jan. 27 10:00am update - or some such).

For some reason my brain can't figure out how to track the update or changes from the previous day's update.

Does that make sense? What am I missing?

Thanks for any help, 

Anthony