your late in flower. those buds look almost done right ? this is normal when In late flower all the leaves most of them will turn yellow and look like shit , do not feed them more heavy, common mistake, if the buds are turning brown and almost done I would flush with plain ph water , get them ready for harvest, your trying to grow nice buds not leaves. other wise you would of just kept vegging for ever, my opinion. if your pushing nutes to heavy flush for harvest problem solved, and if a difency you flush now and can harvest any time, its a win win flushing,