You should always report something like this, even if you don’t know if anything will come of it. The worst case scenario is that they’ll decline to give you medical care. The chance of receiving medical care outweighs the annoyance of the reporting process. Make sure you have lots of details, such as when the pain/numbness started and when it is worse than usual. Having exact dates and times will help your case out.
Edit: Your personal health is very important. If it gets really bad, just remember that a minimum wage job is not worth risking bad hands for the rest of your life. This is why it’s important to seek medical care early.