Your peppers were suffering from too much water. Now, they are suffering from too much fertilizer. Fertilizer is not medicine - it won't fix a stressed plant but could easily kill it.
Did you check the bag your potting soil came in? Most potting soil comes with a built in several month supply of fertilizer. In a container, fertilizer should be mixed at 1/4 to 1/3 the recommended strength. Double whammy - way too much water and way too much fertilizer.