Past Posts Resulting in Blank Page, New Posts Revert To Blank Page After Publish

I have a blog at http://florencekerns.com . I am running WordPress 4.8 with Apex theme.

I noticed a problem when posting last week; I would write my post and publish as usual, and after publishing the post would load a blank page on the live site. On the editor page on the backend it would load with all my text turned to white (at first I thought it was blank, but then highlighted and found it was there, but white).

The page does not return any kind of error on the live site, no 500 or 404 or anything. When I view the page source code, my post text appears to be there as it should be, but the page is appearing blank to the user. It is also taking a very long time to load.

I have cleared my cache and tried loading in different browsers with the same result.

After experimenting with creating test posts, I thought that the problem was tied to the addition of a featured image. But then I went to access my old blog posts and found that they are having the same problem.

This problem seems rather suspicious, and obviously is putting a wrench in my blogging if no one including myself can see my posts. If anyone has experienced anything similar or has any suggestions I would be happy to hear them.