Comparing data in multiple rows

Hi,
I have a spreadsheet containing donation data for a non-profit organization with over 25,000 rows. The spreadsheet contains a lot of data, and is sorted by donor name, donation date (when the donation was made) and the feedback date (feedback on how the donation was used).

I'm looking to analyze how many transactions were made by a donor within 10 days of receiving feedback for a previous donation. The condition to check for is
(donor name is the same) AND (donation date >= feedback data for a previous donation) AND (donation date <= feedback data for a previous donation + 10 days).

How do I best perform this comparison? For instance, a donor may have made 20 donations, so I need to compare these donations amongst themselves and flag the ones where the donation date within 10 days of the feedback date for any other donation. I need to perform this exercise for each individual donor.

The purpose is to assess how effective the feedbacks are, and if they're resulting in repeat donations.

Any help will be greatly appreciated. Thanks in advance.