since you finally posted in the right forum....
those are calcium deficiency freckles. i don't advocate the mindless use of cal-mag, but this is a case where i think that's exactly what you need.
in the future when you have a problem, you'll get good useful answers a lot quicker if you tell people what kind of medium you're growing in, what kind of lights you're using, what kind of nutrients you're using, the temps, Rh, ph, and include a couple of pics of the effected plant, one of the problem, and one of the whole plant, so we can see where its starting, which makes a difference. (look up mobile and immobile nutrients)
