When you catch a cold, you get a runny nose. Is snot your body’s way of combating a viral invader, or is th?

Answer 1

You CAN continue the question in the details section, you know.

Answer 2

In answer to your (half) question. Viruses which happen to affect the respiratory system and make our noses run, and make us sneeze, are more easily and efficiently spread (via airborne droplets), so they will be more prevalent. So, it is an evolutionary adaptation by the virus.
Mucus production is good for trapping and eliminating dust etc, but it'snot much good at getting rid of viruses, because they have infected the cells lining the airways, and are reproduced and then carried away and spread by the serous (aqueous) fluid produced due to the irritation of cell lining.

Answer 3

I'm not a doctor but I am an avid watcher of Dr House. My guess is that you may have blown your nose too hard and ruptured your sinus membranes. I'd say try some decongestants to clear up the excess mucus. Avoid blowing your nose as much as possible to not cause any further rupturing