If you've had a cold for a few days and are now coughing up darker yellow mucus, it's still probably just a cold. If you continue to cough up dark mucus after a week, it's a good idea to see your doctor. If the cough feels deep and makes you feel short of breath, it's probably more than a common cold. These may be signs of something more serious such as bronchitis or pneumonia. Call your doctor immediately and stay home from work.
If you have pain around the eyes, top of the forehead, the cheekbones and even the top of your teeth, it may be a symptom of a sinus infection. Go ahead and call in sick. Then call your doctor. You may need an antibiotic or other treatment to relieve your sinus pain and symptoms.
What's causing those aches and chills?