Hi eliij,
Thank you for using the Apple Support Communities! We understand the rear-facing camera on your iPhone 7 Plus is shaking and we want to help.
You mentioned already trying some steps on your own. Take a look over this article, and complete any remaining steps to see if this helps: If the camera or flash on your iPhone, iPad, or iPod touch isn't working - Apple Support.
If the issue remains, you may want to have your iPhone evaluated by an Authorized Service Provider. Depending on your location this may be an Apple Store, Apple Authorized Service Provider, or Apple Authorized Distributor. This site will help you to locate the service providers in your region: Apple - Find Locations.
Before taking your iPhone in for service, you’ll want to be sure to have a backup of your data. This article will provide you with a link to follow for how to backup your iPhone, as well as other steps you will want to take before your service evaluation: Get your iPhone, iPad, or iPod touch ready for service - Apple Support.
You can also contact Apple Support directly to discuss any other options in your area: Contact Apple for support and service - Apple Support.
Best regards.