Um school question? Please help. ?

Okay so I'm in middle school. I miss a lot. But I get sick like a lot, an it's in my genes. My aunt gets sick a lot, my great grama did, and so on blahh. K so, I miss almost every week. It's not my fault! I really try and go to school, but there's like something wrong with me! I get so tired I can't even like open my eyes. And then I usually get like a fever, or I can't stop coughing. I've been to the doctors numerous times, but they dunno. I got my blood tested today, my mom wants to see if I have Mano. Or else thiroids (which runs in the family also). So yeah. Well, my teacher HATES ME. I have no idea why! I do extra credit, get all the missing assignments in as soon as possible, and I'm nice! I mean I don't have bad grades, but she still doesn't like me. My other teacher (math,science) likes me. But my reading,s.s,English,religion, teacher HATES ME. she will like talk to me about this and my mom has talked to her a lot bout it and she's nice then, but she doesnt understand! She's really hard on me too! What can I do that will make her not hate me? And how many days can you miss till you have to repeat..?