I just upvoted you having hurt your back ? sounds kind of wrong to do :)
So sorry to hear cause that sort of injury can take a bit to recover from. The wait for the pain was the inflammation catching up to the injury. I had similar thing happen so I can relate. Good news it you will recover just take a bit.
Just remember being an American the ER bill will be enough to provide housing for a family in another country for 2 years. So do not feel bad for upvoting it. I am gonna need the extra money to pay the bill lol