I'm just falling apart?

For the past few weeks every afternoon I start feeling like I'm coming down with the flu. After lunch I get a headache, and I just feel run down. But when I wake up the next morning, I feel fine. For like, 2 minutes. Then I just get tired out during the day. All these wacky things are happening, and I'm not sure if any of them are related, but I guess I'll just list them all. For starters, I've been really thirsty lately. I try to ignore the thirst at school and just drink when I normally do, and not anymore than that, because if I drink even a little bit, I have to pee 4 times the amount. It gets annoying at school. When I come home from school I drink and drink and drink, and then pee and pee and pee. I'm starting to have these episodes again that went away, and now are back, where I'll eat some food and then fall asleep. I don't want to fall asleep, and I try really hard to stay awake, but I end up sleeping until my body lets me wake up, which is usually hours later. The other afternoon I ate some oreos and slept for 5 hours. This isn't normal. I have an extremely strong bladder, so I can hold my pee better than anyone I know, but I'm still peeing more times than usual, and when I do pee, I pee a LOT. Yesterday I was really busy and didn't get the chance to pee for like, 4 hours, which wouldn't be a big deal, but I started to get a stomach ache and when I did pee, I peed like, 2 cups. Literally. It was so much pee. And then my stomach ache went away. I don't know if any of this stuff is related, but I've been getting more headaches lately, my lips are chapped, my eyes sometimes start to sting like they're dry, and LED or LCD or whatever lights like on clocks and scoreboards look weird to me, like someone smeared them with their hand. My foot sometimes starts having a really bad pins and needles feeling that makes me want to throw stuff. It happens in my hands too. My scalp is SUPER itchy and dry. I'm itching it so much I'm leaving scabs. I had a canker sore a while back that shouldn't have even turned into a canker sore. It was just a bump in my mouth that got infected and took a while to heal. It was really painful. Plus I have this recurring cold sore thing on my lip that came back out of nowhere. It's painful as well. There's a bruise on my leg from last week when I fell up the stairs and smacked my shin on the edge of a stair, and it left a big welt that's still there and it still hurts when people bump my leg or when I touch it. It's not any better at all. My skin's just really dry in general, which makes no sense because I'm drinking more water now than ever. Sometimes after I eat I get really nauseous and dry heave, but I don't actually puke. One time after dinner I did puke some of it up. That was weird. Sometimes I get pain on the left side of my stomach. I feel like I can't get hydrated because I'm peeing everything out, and I can never get full so I keep on eating. I'm just a disaster. If anyone has any idea what this might be, or if it's just a virus that will go away (although I've never had a virus for this long) I just don't want to go to the doctor because it's not like I'm dying or anything. I'm afraid I'll go to the doctor and they'll tell me I'm fine. That's always annoying. Any help would be greatly appreciated! Sorry this is so long!