If you believe those numbers, the next thing to do is add bleach.
If. I find 19 CYA hard to swallow, if you've been dumping powdered shock in.
But
if you believe them, then you need to add 3 gallons of 6% bleach. And check it again in an hour or so and replenish it to get FC up to 12ish. And keep doing that as often as you can until the water turns clear. It's going to take a lot of bleach and a lot of time. Check out this thread:
first-time-shocking-with-bleach-t45074.html. Scroll down to the last post on page one.