You must follow your doctor’s advice. If you don’t, then you will not only make it harder to recover fully. You will also make it harder to receive full compensation for your injuries.
Every car accident victim owes a duty to mitigate their damages, and this includes receive prompt medical attention, following your doctor’s advice, and attending regular checkups.
For example, if your doctor advises that you stay off your feet while you recover, then you should certainly do that. You should not go out partying or riding a bicycle, which only risks harming yourself even more.
Car accident victims should also avoid self-diagnosing their injuries. Wikipedia is not a substitute for a doctor’s advice. If you do not feel you are improving, then reach out to a different doctor for a second opinion. But do not simply start self-medicating yourself.