With a FC below minimum on Ben's Best Guess Chart and a significant CC reading, I'd say the cloud is probably the beginnings of an algae bloom.

I recommend you shock this pool. Shock is a verb, not a noun. Here's an outline of the process:

Add enough bleach to bring the FC above the shock level for the pool's CYA accoring to Ben's Best Guess Chart and keep it there.
Run the filter 24/7 cleaning as necessary.
Test the chlorine and add bleach to keep it above shock level, at least twice a day - more often is better.
Brush floor and walls of the pool daily.

You can let the chlorine drift back down to normal levels (never below the minimum on Ben's Best Guess Chart) one day after meeting all three of these measures:
The pool is clear.
The pool loses no more than 1ppm FC from sundown to sunrise.
The pool has nearly zero CC (less than one drop).

How are you chlorinating?

Sorry Ben, I was posting at the same time.