If you just removed that many pictures/videos.. did you also clear them from the Recently Deleted Album? I'm guessing you did because I don't see a Recommendation in your screenshot to empty this album, but thought I'd make sure.
You can use the Contact Support link in the upper right of your screen so that Apple can troubleshoot 'Other' storage issues on your device.
Get Support
OR you can do the following:
Backup/Reset/Restore your device, review these links:
How to back up your iPhone, iPad, and iPod touch - Apple Support
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support