Pale/yellowing leaves, rust spots, tip burnt, stiff plant and leaves

it's more likely lockout or toxicity + lockout than anything else. ensure pH is correct for soil -- 6.5-6.8. the soil as well as what you feed. Do you irrigate until 20% runs out bottom? if not start doing that and toss the water out or outside. I'd give an irrigation like i describe of pH'd water without fertilizer. then go back to regular cycle if you alternate fertilizer / water-only etc.