Also keep in mind that over fertilizing with high end nitrogen fertilizers can cause problems (even time release types, especially in warm weather). My experience has been that an excessive build up of nitrogen in the plant tissues creates a situation where they are much more susceptible to pythium and phytophthora pathogens.
From what I see in the photographs the likelihood of recovery seems slim, however do not give up. Also, all is not lost if the plant(s) die. Such situations can be very good learning experiences. I like to look at all the various aspects of the plants culture to analyze what might have gone wrong or could be done differently for the benefit of the plant. This way I learn and am a better gardener.
