Help please turning yellow fast

Hello I am new to this and am having problems with my plants. I am using sunshine mix4 and NSR greenleaves grow juice and boost juice once a week. The plants are about 8 weeks old and are just now starting to show problems. My lower leaves are where I first notice this and the leaves are tuning yellow with brown spots. My first guess is mg but the stems and veins are really purple/red. It is now getting worse and moving up my plants turning more and more leaves yellow. The first ones that showed signs are now almost completely yellow and brown and dying. I will post pictures today but please help more plants are starting to show signs.

Need pictures

I have posted pictures in my proflie would not let me attach to my post? Please look at them and let me know what you think

When is the last time you transplanted?

helo, im new member here n i cannot find my way around as so big n so many threads, i dont no if u will even notice my post ere, n im so so sorry if im cuttin anyone elses post up here i do apologise.
my problem rite now is spider mite, but i live in the uk n as far as i no the > no pest strip < is not available in uk as a chemical that is in the no pest strip is harmful n so banned.
so then, can any1 please please help me, iv tried everything else in uk but really need sumthing like no pest strip cuz im member everywhere n all im seein is that product bein praised, can any1 help me in anyway, wat can i use that will stop em dead, im 5 week away from cuttin down n they spreadin fast, iv tried sprays etc, but want somet like no pest strip, help me pelase sum1 !!!

this particuler plant was transplanted about four weeks ago into a three gallon bag.

Unless the yellowing and dying of leaves becomes widespread I wouldn't worry about it.

It is taking over the whole plant it has moved from just the lower leaves to now up the plant and on to some smaller leaves. I am lost at what to do right now and need something fast before i loose her and other plants start to show signs and i loose them. Please help me figure this out.

fill out the troubleshooting form (in my sig).

-shake

No mention of soil or water Ph? You can use the best nutes in the world but if you Ph is out of whack the lock out will not allow the plants to take up the nutes.

What's your Ph?

Yes, fill out the trouble shooting form unless you want blind guesses.