before doing anything - you need to purge air from the system, checking the level time and again on that model civic is a sure way to ensure you trap air in the system. Ensure you have the thermostat valve in the engine to maintain an even temperature throughout the engine and it operates correct. Also make sure the overflow pipe is secure, has no holes and goes all the way to the bottom of the bottle.
to check for headgasket, start the engine in the morning and open the cap after 1 minute, if the pipes became hard and the cap shot off with pressure you have a bad head gasket. Before doing this check the pipes are soft with no pressure - also note that in this condition if you remove the cap you might hear a "hiss" sound this is not pressure it is air being filled into the vacuum in the system.