The yellowing is a Magnesium deficiency.
Remember too, what is showing in the leaves now, is a direct result of what was happening in the root zone 2 weeks ago, that is why it got worse overnight, your plant has 2 weeks of deficiency already.............it will take 2 weeks to correct, but once you up the cal/mag, symptoms should slow down and stop eventually, but the damaged leaves will stay damaged.
The brown blotches are nothing, most likely caused by something dripping on those leaves, or mechanical damage from hitting the edge of the pot or soil surface.