Sounds to me like bug droppings or something eating the plants as for the black dots and the yellowing sounds like a nitrogen lock out problem bump your pH to somewhere close to 7 and see where it goes and add the same nuts.
After quiet a bit of thinking I have come up with this answer if the DEAs green thumb department were to have a link with your local power company for say AEP and they had a program in theyre computer that would red flag people that had a high power consumption within a 12hr period and then...