Anyone know what this could be?!?!

This plant has been yellowing for awhile, which I though I had taken care of but just within the past couple days these black spots started showing up. At first I thought it was a phosporous def. so I added a little bit of Tiger Bloom to remedy that but now they've gotten much worse. It's actually showing up all over now. Does anyone know what this could be? I'm stumped. ANY help is much appreciated.

repot your plant using different soil. Dont use soil with white chunks of nutes in it already and make sure to add materials for good drainage. Your plant is selectively burning which means your water is probably not evenly being distributed in the root mass. Make sure you ph balance your water and you control whats going into your plant. Your plant is burning from too many nutes but starving because the nutes arent available to the plant = your PH is probably off.

I dont think the soil is the problem here. Flush your plants with pH'd water. Check your pH and check it again. See how they react to the flush.