Hi mate, this looks like a PH issue. When the PH isn't right is will cause a slight lockout and stop absorbing nutrients. Calcium and magnesium are the first to show up with a pH caused lockout. Perform a slurry test of you soil and adjust your watering ph to suit. Had a similar problem with mine recently and realised my meter was faulty. Plus I added too much gypsum at one point, lowering the soil PH. She has bounced back in no time. I hope this helps, good luck and happy growing