Yellow Tips and Brown spots on my Super Lemon Haze. (with pics) Please help.

This problem is getting much worse. I would say the yellow tips go up 75% of the plant now and the brown spots are all over the place now and really big. The brown spots go up the plant about 50% of the way and about the size of a dime. If it is a nutrient deficiency, I'm going to use fox farm grow big (6 -4 -4) at 2 tsps per gallon to give it a Nitrogen boost with cal-mag (2 -0 -0) at 1tsp a gallon. I'm still a little worried that this is nutrient burn though and that increasing the nutrients will push my girl to its imminent death. The last time I fed the plant was pure water but it was only getting 6 tsps of foxfarm Big Bloom (.01 -.3 -.7) before that. Now I will be going up to 6tsps of foxfarm big bloom, 2tsps of grow big, and 1 tsp of cal-mag. I would love to get everyone's opinions on this choice. Thanks again to Dreamy for all the advice so far. Much love brother. . Starting to get a little worried that I won't make it to the end of my first grow.

Pics of my sad girl

I tried the cal mag a few days ago and have not seen any improvements at all. If anything it has gotten worse. Two of the lower fan leaves have fallen off. The leaves that fell off showed the same symptoms as the newer growth on the plant. I included pictures of the growing problem as well as some of the grow tent that they are in. Could definitely use some help, I really don't want to lose my girl.

For your next grow just keep flushing the plant with pure water, and make sure the water is PH tested to around 5.7 - 6.3. If you have it too high, which it most likely was it will make the plant get dry and normally yellow crispy tips.