OMG!!

Rest, apply ice packs to your arm and probably your back, which will probably be hurting tomorrow.  Take Ibuprophen for the pain and to reduce the swelling.

Did you get checked out at the ER? If not you really should go. The body is not meant to be thrown up in the air and land on concrete. Plus it will help with any claim you have for physio, which you may find you need.  The car driver's insurance should cover that for you and any other medical costs that you incur, even loss of wages if necessary.

Take care :)

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi