I would suggest you do NOT add any more CYA. Most folks on this forum think that the ideal range is betwen 30 and 50 and you're already at the high end of that.

Over time with rain and topping off then backwashing, the CYA will creep down, but only very very slowly. Check it again in a week to see if it's still near 50. The I would suggest you only need to check it once a month or so.

Now that the CYA is up your chlorine levels will stabilize somewhat. They will go down more during the day with sunlight being the biggest factor, and swimmer load the other. Because it gets blown away by the sunlight, top up the chlorine in the evening, after the sun is off the pool and that will keep the levels pretty much where you want them all night an into the morning hours of sun a bit. Then it will slide through the day, till you top it up in the evening again. You will see the cycle. After a while you'll see that on a normal day you need a half gallon of bleach or whatever.

good luck and enjoy