Looks like your CC is very high at 4.5
Your PH is low at 7.0
You need to adjust your PH back towards 7.6
Then shock the pool until your CC is <= 0.5
Then add CYA to get it back to 30-50.
You can use di-chlor for shocking, but it is more expensive that bleach and stabilizer last time I checked.
You could have been hit by what others are seeing on the forum where you FC drops to zero, then you CYA changes to CC. I've had this happen myself a couple times.
hope this helps,
P.S. - the pool calculator can give you all the proper amounts.