Yellow, Light Green Leaves with red stalks and veins

Have one plant that's been giving me problems for a while now. Got it from a friend and when it came into my room it didn't look very healthy at all. A very light shade of green throughout the plant, but I decided to see what would happen after a few days. After a few days, the leaves started to turn even lighter and more so yellow with red stalks forming and red veins. My first instinct was to flush it and see where the run off water was at as far as ppm. On the first gallon and a half, it pegged the max level on my ppm meter at 2200 ppm and the ph was in low fives. I continued flushing until I was able to get the ph up to mid 6's and got the ppm down to around 300. I let it sit for a few days to let the soil dry up a bit, then I gave it a light watering with ph'd straight h20. A few days later I gave it a light dose of Fox farm grow big, and big bloom just because I had run the ppm down so far in the soil and from all the research I've been doing on rollitup, the signs pointed to a Nitrogen deficiency? The plants are 2.5 weeks into flower but the concern for nitro deficiency is why I gave small dose of veg nutes. All my plants are in soil, royal gold basement mix to be exact and besides this one, the rest seem to be doing just fine. The sickly one doesn't seem to be getting any worse, but also doesn't seem to be getting any better. Just wondering if I was on the right track with my treatment of this plant. I take that back, the newer flower growth and surrounding foliage is coming out looking healthy but it seems like the rest of the old leaves are still light green/yellow. Should these recover? Will the stems and veins return to green? I wish I had some info on the strain, but there's not really a name for it, just something that's been grown around my area for a long time. I have one other of this strain and it looks healthy as a horse. Any input is much appreciated. Thanks!

p.s. - I would upload pictures but just have a crappy cellphone camera.

Bump??????

Thos yellow leaves should return to green it takes a few days. If the new growth is normal then the plant is fine.just don't over feed it with too muchj nitro take it slowly