It definitely sounds like something got broken when your phone fell. How often does the boot loop happen? Do you have enough time for the phone to boot and for you to sign in? Generally a boot loop caused by a bad sensor goes in three minute intervals; the length of time between sensor scans on an iPhone.
If that's the case, we may be able to pin down the cause for the boot loop so you can replace the right part without having to take a shotgun approach of randomly trying to replace parts in hopes you'll get lucky and fix it.
There's a great guide to iPhone kernel panics available here on iFixit that you'll want to take a look at. A kernel panic is what the operating system does when it encounters an unrecoverable error. It logs the error then reboots the phone. Here's the guide for you to read.
iPhone Kernel Panics - iFixit
If you can get into the phone and access the panic logs, take a screenshot or cut and paste the first page or so and add it to your question.
Adding images to an existing question - iFixit Repair Guide
From there, hopefully we can point you to what's causing your boot loop so you can fix it and get your phone back to working order.