Keep working to get your ph in the range of 7.4-7.6. Wait a few hours after adding doses of muriatic acid to let it circulate. Then retest and redose til you get it down.

It will take about a week for the cya to dissolve. Add it to the skimmer (don't broadcast it across the pool like some containers tell you to) and then don't retest for it, add more or backwash for a week. Until you start to get a cya reading, it will be tough to keep any chlorine in your pool. You'll need to test morning and evening and each time, add enough bleach to take your FC back up to about 5. (In your pool, each quart of 6% bleach will raise your cl reading by 1ppm.) After the cya begins to dissolve, you'll be able to just test and dose it with bleach in the evenings. (Adding 4 gallons of bleach was way too much for your pool. In a 15,000 gallon pool, 4 gallons would take your cl reading up to 16 which is way too high when you have no cya. I hope it doesn't bleach out your liner!)

Hope this helps.