Cal def ?

Definitely not a calcium it looks more like a potassium deficiency. The perfect picture really it's showing all the signs. What I'd recommend is that you find a chart for your medium type whether it be coco or soil for the uptake of nutrients. Find potassium and then you know roughly where abouts the pH should be of the medium for it to begin to take it up again. Flush it with the correct pH and keep checking run off. If you have some also organic seaweed also I'd be using that too.

Unless your using RO water, your probably overloading on cal/mg. Now that their in flower I would cut it out altogether or maybe every second water change, add half a teaspoon.

Check PH, if u feed enough nutrients u probably have Pottasium lock out.

Potassium deficiency