Asthma is a most likely cause, but there’s also a possibility of (if you’ve done any heavy lifting or excessive exercise or anything that could push your body too much) having a pulled muscle in your back or somewhere close to your lungs. I’ve had the pulled muscle one and it was very hard to breathe for a couple of weeks. Try to convince your parents to take you to a doctor and if they continue to refuse, just make an appointment yourself and explain to them that you’re worried about your health