Please help me - question about grades and school?

I have been sooo stressed lately about my grades! I'm never hungry (even though I normally love food), I never really want to do much of anything, and the only thing that I ever do want to do is sleep for hours because when I'm asleep I obviously can't think about my problems. I've even thought about suicide, although I don't think I could actually bring myself to follow through with it... Anyway, I am 15 and a sopre in high school. I've usually made all a's in the past, but now all of a sudden I have 4 a's, 2 b's, and a d in math! This is a huge problem, especially the math grade of course, and I am afraid to imagine what my parents will do when they find out. My school has parent-teacher conferences a week from today, and since the first quarter is now officially over, there is nothing that I can do to improve my grades before then. I am so scared about what my teachers will say to my mom and I at the conferences. My parents expect all a's, even though most of my cles are honors or ap, and I am sure they will be furious once they see my report card. I know that I could have done better, and I feel guilty and ashamed of myself as well as terrified to see my parent's reaction. So yeah... please help me! Please! I've tried talking to my friends about this, and while they try, they're mostly straight-a students who really can't understand what I'm dealing with. I get that this is mostly my fault; please don't make me feel even worse! All I need is some good, uplifting advice! Please... D: