help with brown spots and yellowing of leaves...

I've got this problem for the past two weeks, which I first thought was nute burn, so I flushed the plant a few times, but symptoms just got worst. I've just fertilized it with big bloom, tiger bloom and cha ching, but still getting worst. the problem are starting to affect the flowering leaves; the plant is just not looking good. Doing some research I though this may be either a calcium or manganese deficiency....





any thoughts? I'm 8 weeks into flower, and the buds look far from done...

- looking at cha ching supplement, it has some manganese...

looks like calcium lockout or deficiency.
do you ph your water?
do you use ro water?
do you use ph up?

I use filtered water, I don't mess with it beyond that. tested the ph of the soil yesterday and it was around 6.5-7. gave it some ca-mg yesterday also, we'll see what happens. No signs of improvement yet.