Helping People

Am I liable for giving first aid without a medical license?
My cousin is a qualified doctor; so from her I have learnt how to give first aid in case there’s an emergency. Now the other day I gave first aid to a guy who was playing football with me. What I’m scared about it is, this guy hates me and might take a revenge saying that I treated hum without having any qualification of a doctor? Please advice
Can I sue a doctor for negligent emergency treatment without payment?
I met with an accident and somebody carried me over to a doctor’s clinic and he stitched my wounds. He received no remuneration for that. But he did it a wrong way. Later I had to treat it again. Can I sue him for that?
Am I liable for a person's death after providing first aid?
I gave first aid to a person who sustained severe injuries in an accident. Thereafter I took him in my car to a hospital. Unfortunately, he died while carrying him in my car. I wanna know whether I’m liable for his death.
Can I sue a nurse for injuries sustained during emergency treatment?
I met with an accident and somehow a nurse who arrived at the accident scene gave me first aid. I sustained some more injuries during her treatment. Can I sue him for that?
Can a patient sue a dentist for follow-up care after emergency treatment?
I’m a dentist and I fix a person’s teeth that were broken in an accident at his workplace. I rendered the service only because he called me in an emergency situation. Now he is coming to a follow-up treatment that too he is not ready to make any payment. He says I’m liable for the follow-ups since there is a doctor-patient relationship. Can he sue me if I didn’t treat him?