Severe sulfur deficiency, to start. Those red petioles are not good!
It looks like you have a general micronutrient problem... either your pH is off or you are not feeding enouhg or you are locked out. But I am not seeing signs of toxic salt lockout so I am guessing pH imbalance or simple starvation.
The spotting could be caused by Ca or K def, or (less likely) a fungus, but even a fungus is often a side effect of the plant's immune system being weakened by a lack of potassium.
So flush, check your runoff pH, adjust if necessary, feed with a complete bloom fert.
If I had that problem I would also add a dose of a micro supplement like GH Micro or Algoflash to the next feeding.
Oh! Last thing- if your temps are very high that will certainly intensify the symptoms.