Custom Feed – feed-rss2.php

I am trying to add a custom feed file, feed-rss2.php to the theme folder.
When i add my custom file, my feed stops working completely.

This was currently working with our old theme, and has since broken since switching to the paid, pro version.

How can i fix this, We also have a custom api.php, which used to be accessed by https://myblog.com/api.

This also no longer works since switching themes

Thanks
brian