DB Script help

I have a table which captures table and index size. This job runs every day and insert the details in a table

Capture Date/Schema Name/Table Name/Size

Please help me create script to get delta change of the table size for a day..(Current Day-Yesterday's Size). Also what is the best way to find out how the size of the table increased? like whether its due to a job or updates from app server or .

Regards,

Arun

Best Regards,ACDBA