If you haven't added any more CYA, then it's not going to rise overnight--save the reagent until you've added some CYA, and then give it a few days to dissolve before testing for it. The FC will not stay that high for very long, with a low CYA. One or two days of sun should bring it down substantially (in my pool, it would only take one day!! ). When eyes are bothered, it's usually because the pH is too high or too low, or because the pool has lots of CC due to inadequate chlorination. A properly chlorinated pool shouldn't be hard on the eyes.