iPhone 5s' battery swelling?

Some months ago I noticed the bottom left part of my phone’s screen was lifted up a bit. I had dropped the phone on a wooden surface once some time before that, but when i picked it up at that time I didn’t notice any damage, so I’m not sure that was the initial cause.

As time passes however I see the screen lifting up more and more, right now the bottom left part is considerably lifted up and it has extended to the top left part of the screen. Then I decided to look into the problem and reading about it on here and other sites it seems a swelling battery might be causing this. I’ve had the phone for 4.5 years and it has over 1000 battery cycles, so it is probable, however I want to be sure. Is there a way to check whether it’s swollen without disassembling the phone? Or is that enough proof to know it is?

Also, should I keep the phone in a safe place or is it OK to use it until I get a replacement?

Thanks in advance.