I dropped my phone and when I shake it, it cracks inside

Hello~ Don’t shake it anymore. Have you backed up your iPhone?

Back up iPhone - Apple Support

Also…

Find information about your warranty or AppleCare plan - Apple Support

Go ahead and make an appointment with Apple to see what your options are at this point.

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~Katana-San~

You need to have Apple perform diagnostics on your iPhone. It can be done in person at an Apple Retail Store or at an Apple Authorized Service Provider. You can also contact Apple Support and request remote diagnostics.

If you’re in the US, please call  1-800-MY-APPLE, or outside the US, consult the support articles below. In Canada, call 1-800-263-3394.

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Genius Bar Reservation and Apple Support Options - Apple

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This sounds ominous, if the phone gives a rattling sound when you shake it something has broken off or has come loose. Take it to an Apple genius as an emergency, for diagnostics and repair, and don't shake it, might make it worse. Good luck.

This is what's technically referred to as "a bad thing"...

The warranty does not cover accidental damage or abuse.

The diagnosis will probably be free but the repair won't be. The one year warranty only covers manufacturer defects, not user damage.