The past 3 days I have been coughing stuff up, my throat has been burning, and my voice has been gone. What could this be and how can I treat it?

Possibilities... Your symptoms could be due to an upper respiratory infection, probably viral if you are afebrile. If this is the case, it will run its course over days to a week or so. It could also be due to allergies which would require a doctor evaluation and treatment. So, see your doctor so you can be diagnosed and treated.
Time to see your MD. If this has been going on for 3 days and is getting worse, you may need an x-ray and antibiotics. If you are having fevers, shortness of breath, and weakness this is a must. If you are a smoker, this is your body begging you to stop!
Cough. This time of year cough from various viruses is common. Treatment is aimed at relieving symptoms. Use a clean humidifier or vaporizer to add water to the air. Rinse the nose with saline to remove mucus and relieve swelling of the tissues. Honey lemon tea helps soothe the throat and honey suppress cough (for >1yr olds). If blood in sputum, difficulty breathing, or symptoms >2wks - see your doctor.