What can I do- I want to go to school but I'm always sick and my teachers don't understand?

It seems to me that you and your parents need to schedule a meeting with all of your teachers. As a parent I wouldn't let any of this slide. Your teachers have no right in saying the things they are. It just seems a bit odd to me that EVERYONE is accusing you of lying. Is there a particular reason for that? It can't just be coincidence. I don't what else to really say, if you are being honest and you are really sick (which I am sorry to hear) than your parents need to go in and have a talk with these people. If that's not an option, than do it yourself. Good luck and I hope you feel better soon.