I had no idea what the problem might be until you mentioned you are in Florida. About this time of year there, tomatoes often turn up their toes and croak - too hot, too humid. Could also be if you had planted them right out with the soil in your yard - it's very sandy, and there are not many nutrients in it since, every time it rains, all of it gets washed down into the aquifer.
Best time to start your toms in FL is February, that way they are done right about now. You can start a second crop, indoors, in August and transplant them outside in September.