Painful, sore, red gums can be a symptom of gingivitis (inflammation of the gums) or, more likely, periodontitis (inflammation of the attachment fibers of the teeth and supporting bone), which can arise due to a number of different causes.
klick (plural klicks) ( 1 slang, military) A kilometer. 2002, Robert J. Sawyer, Hominids an asteroid between one and three kilometers wide had slammed into the ground at fifteen klicks per second. ( 2 slang, usually in the plural) Kilometres per hour.
1 click is 1 kilometer. It's also used by Army personel to pace the distance they walk. Because the normal distance of a person is 66 steps for 100 meter, soldiers use counting beads to count their paces. By counting the steps they can get a pretty good guestimation how much terrain they crossed on flat surface.