I would check your ph first. It looks like you are not giving enough potassium for flowering. Which if this is low your substrate ph will climb out of range causing lock out. The spots are calcium, and possible potassium deficiency spots mixed in.
You are right those are signs of calcium deficiency. If you have cal-mag start adding it as instructed on the bottle for it to start fixing as quick as possible. Good luck with the rest of your grow.