Tip burns and some spots on the leaves

Been feeding organic nitrogen every week of veg and 4 weeks into flower, that's probably not a good idea, lots and lots of ammonia, the plant uses less and less nitrogen as flower ramps up, the microorganisms ramp up and release more nitrogen until the ratio of nutrients skews ph, that's where your nitrogen tox is from, your tips are also showing clear signs of the medium having too high salt/nutrient content. Give your plant a good, solid flush with lots more water than you normally would; the ammoniacal nitrogen will need 3-5 times more water to separate it completely from soil particles. once stripped of everything, ph back between 6-7 then go back to feeding a regular flower schedule of feeding, making sure to control the salt ion capacity of your medium, no more grow.

Mg excess, Ca,K,P lock