Why leaves brown? (urgent)

you are having a ph issue in turn is creating a lock out. how to fix is easy, flush until your run off ph is at a 6.0, let the pot dry out for a few days, as when you flushed you are using water to clear out what is in the grow medium. after the pot has dried out probably 2 days , feed at half of what you have been feeding and add cal mag to the mix, makes sure to keep your ph in line. also when you flush pick your pot up so you know how much weight your plant has when full. last pick or cut off the damaged leaves, they will not return and by keeping them you could possibly get mold. so any dead or dying leaves should come off. hope this helps