Before you even get your pH tester I can tell you that your fertilizer is causing your problems. That's azalea food. First off it's quite concentrated, and of course the pH is lower than you want. What you are seeing is the beginning of a lock out. Even though it has the Ca, the plant can't use it becasue the pH is too low.
So flush out your soil really really well and switch to a cannabis-specific fert or at least one that is just general purpose. If you use a different 30-10-10, use it at like 1/3 strength and feed just a bit more often.