Hopefully, there is a record of your fall from when it happened. You might try telling your sup that the back is still bothering you and you need to be seen by a doctor. Working with an injury, or pain can lead to more injury.
You really have to push sometimes to be heard when it comes to comp cases. Some doctors, but not all, treat comp cases as if the person just doesn't want to work. Be real, be honest, try the treatment they offer with an open mind. If you still have trouble don't be afraid to let them know.
Although the union tries to stay out of comp issues they should be able to offer some information or tips to help you through this ordeal. Many in here have also been though it and would try to help with specific questions but remember, comp laws differ from state to state so it's hard to be precise. Best of luck to you! dw