Cloudy water makes me think excess organics (over feeding?) I've induced cloudy water a couple times in a 10 gallon while trying to cause an algae bloom (experimenting). Generally it takes 2-3 weeks of moderate to high overfeeding. The nitrite implies the tank is cycling for some reason, and apparently the ammonia isn't building up (NH4 consuming bacteria multiply faster than NO2 consuming ones). This also happened when I induced the (white, not green) cloudy water in my tank.
Is it possible that there is rotting organic matter in the lava rock?
I would be doing 50-70% water changes at this point, but it all depends on ho hardy the fish you have are. I would also cut feeding in half (same amount, but every other day).
edit: Don't clean the filter unless it clogs or overflows. In that case you can rinse the media in a bucket of aquarium water, but nothing more. If you replace the media you'll lose your beneficial bacteria and trigger a cycle.