I probably have spider mites on my plant. Yesterda...

Hey definitely looks like spider mite damage. Usually will look like white peppered dots on the leaves turning the leaf black once it starts to die. There is also leaf miner which will cause the leaf to die, best to just pluck that leaf. The sprays most likely will work if you're following the instructions for them however you could also try Hydrogen Peroxide which is cheaper and typically "cleaner" (no oily mess, not a pesticide and oxidizes) could probably spray the plant on a more regular basis using that but again whatever kills them so you can get the plants back on track. Also the soil they are in looks dry, make sure you're watering enough (around 10% of the pot) and not too much (if it hasnt dried out or drunk what you previously gave it) Nutrients wise it looks fine other than the slight sign of wanting calcium hope any of that was helpful