Hello, and thank you for posting on Healthcare Magic!
It sounds as if you may have some injuries from your car accident.
You need to have some xrays done to look for fractures
in your arm which is giving you such severe pain
. If the xrays show no fracture then likely the pain is just from bruising, which can be quite severe.
Xrays of your chest should also be done for a couple of reasons. You may have broken ribs
that cause you to have pain with deep breaths. There is not a lot that can be done about this, but it is helpful to know so that you can be careful as they heal. Also, it is possible for the lung on that side to be collapsed due to the trauma of the accident. Usually nothing needs to be done and the lung will heal on its own. But if the lung is severly collapsed you may need a "chest tube" to be inserted, so that the lung can re-expand. The chest xray will also make sure that you don't have pneumonia
I hope I have given you some useful information, and I wish you the best of health.