I'm guessing you've caught some kind of flu bug, so here's my tips:
You need to have the largest cup/bottle in your house right next to you at all times, filled with water. Just keep sipping it, all day long. You should go through 2x-3x the amount of water you normally do. The extra water helps thin the stuff out, making it easier to cough up/your body to eject. Also, since your heart rate is running around 40 beats faster per minute (because your fighting this stuff), it needs the extra nutrition, and water is the best thing you can give it.
Even if your nose is no longer stuffy/runny, BLOW YOUR NOSE, DO NOT SNIFFLE! Sniffling causes the mucus to run down the back of your throat, which could be what caused your throat to be raw in the first place.
If you have strep throat, combined with some sort of cough, then you REALLY need to see a doctor. Have your mom/a friend shine a flashlight in the back of your throat, while you say "aaaaaaaah", and if they see white spots, you have strep. As I said before, this is a sign that you REALLY need to see a doctor. Strep is highly contagious, but the antibiotics that the doctor will give you will have you feeling completely normal in two days, maximum. DO NOT try to sit this out at home, as the longer its in you, the more you spread it.
As far as the cough goes, stop taking the freaking MucinexDM. A. It doesn't work, trust me B. If it does work, the thick syrup that's going down in there to get the medicine to you just doubles the congestion, cause its more crap that can get caught in the sponge that is your lungs. And coming from an asthmatic, who was stuck in bed coughing for two months, the secret is lemon-lime gatorade. Right before you lie down in bed to go to sleep at night, fill up a coffee mug with lemon-lime gatorade, and then throw it in the microwave for around 2 minutes, so that its about as hot as your tea. Sip it until its gone, then immediately lie down to go to sleep. This allows the vapors from the gatorade to make its way into your relaxed lungs, soothing and thinning out the flem.
Hope all this works. If it does, keep your money, I don't need it. I've had severe asthma my entire life, so whenever I get sick/the flu, its 20x worse than most other people's. Trust me, these are the best ways to get rid of crap.