Death of father due to medical negligence

My father died 1 month ago.His ultrasound showed a serious swelling on nerve which a private practitioner said is a medical emergency so we took him to Govt hospital as he was insured there , but doctor who attended my father said that this isnt serious right now, told to show in opd and gave painkillers. Then in govt opd 1 doctor said it is not serious and 1 said it is serious and told to show next day. But my father fainted later on that day and We rushed to take him to govt emergency ward where after some treatment my father died. Also the doctor in emergency ward attended my father a little late and while my father was critical that doctor made me sign on a blank white paper which I did as I was worried at that time. Doctors were unclear at that time what was the reason of death and I also didnt asked for postmortem. So i dont know exactly what killed my father but most probably due to nerve rupture. Is case possible here will it be feasible as there is no earning member in familyn