What are the side effects of inhaling concrete dust?

Not likely. While breathing concrete dust and soot is not good for you, harmful effects generally would come from prolonged exposure over a period of months of breathing high dust levels. Next time, visit the hardware store for a disposable respirator and a small spray bottle. Use a mist of clean water to hold down the dust, and the respirator to keep from breathing it. While we can't make a medical diagnosis, your symptoms sound more like the flu. Go see a doctor.