Rust spots on plant, condition worsening steadily

I think if I were you I'd stop asking the peanut gallery for their random opinions and get down to the basics. ANYTIME you have a plant issue, the very first thing you want to do is collect some runoff data. The vast majority o nutrient "deficiency or lockout" is really just a misdiagnosed pH issue at the rootzone. If your readings check out, evaluate your watering habits. Over and under watering issues cause similar symptoms. Rotting roots eventually show themselves in dying vegetation. If your confident about your watering, start comparing your leaves against other examples to determine what imbalance you could be facing.