Dark green = hyper fertilization
The spots and blotches are from a poor pH
Test your runoff pH, I would guess it`s in the high 5s. there is your problem, the roots are not using the medium and the fertilizer soured in the soil.. Its hard to help those.. I would re-pot it and only use water @ pH7. wait until it dries out if you repot it and use water only @ pH7. They need nothing more than pure water for the next couple weeks. Your soil went sour, killed the roots, the plant is trying to survive by shedding the leaves.. The good news is that your lighting is probably good. You can also help the recovery phase by giving them 50% of the light you are giving them now.
..I would re-pot in coconut husk and feed only water until the bright green leaves start to grow back.