Why do you say it’s not COVID? You can have covid and have no symptoms at all. You can have one symptom, two, three… C is not going to help you breath better. A little C isn’t a bad idea, especially if you aren’t eating well, but It’s no cure. If you lay on your stomach it might be easier to breathe, but if you can’t breathe well don’t wait too long to go to the ER, some people with covid decline quickly and need immediate care. Struggling to breathe is nothing to play with. Also, some treatments work better when given early in the disease. Do your parents not take you seriously because of past situations? That is not unusual for parents to think their children are being overly dramatic. If you really can’t breathe well I think tell your parents again.