I started having mild daily headaches after I had 2 colds in a row in October. The headaches were not severe but disruptive. I've had them for 2 months. They were frequently one-sided, dull and nagging. I also noticed I had a lot of mucus and post-nasal drip. Once I threw up from the amounts of mucus accumulated in my throat.
Anyways, I started inhaling hot steam (just boiled water) with Vicks in it, and blowing my nose after. I was doing it for a week twice a day before noticing any change. Now the headaches are completely gone!