Since you have pain in your lower and upper back after the accident, you must immediately consult an orthopedic specialist or a neurologist. The pain can be due to protruding disc after accident or due to pinched nerves or even due to ligament injuries. You will need MRI of the spine for confirmed diagnosis. Meanwhile please do not over strain yourself. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.