First grow. Pests or Nute deficiency?

OK so like I said this is my first grow. So bear with me please.

I am 19 days past the flip. And within the last I'd say three or four days the older growth has started to yellow and then browning before drying out and falling off. This is accompanied by brown spotting on most fan leaves. The new growth seems unaflicted so far.

I use ferry Morse organic potting soil. The pH rating shows as 6.1. It is in a 10in pot.

I flushed right before the switch and have feed with a 1-2-1 feed at half strength once.

I have her under a gently breeze most of the day light hrs.

With 5 23w 2700k bulbs 4 in away from the top of the canopy.

She has been topped once and under gone minor binding tr hiaining.

Oh yea and I've never founda pest on her in any inspection.

So anyone have a clue what my baby needs?

hi, I think as you flushed before flipping and have only given a small feed since you might be having a cal mag problem, if you flushed heavily then you proberly have got rid of all trace elements, when was the last time you re-potted? I like to do it the last week or 2 of veg, are you using ro water at all? you might want to compare your plant to others online with cal mag probs, to be leeching like that allredy is in my opinion too soon, id try bio bizz algamic for the organic way or some cal mag for sure, at least a good feed with something that has very low n, was your ph the run off??
good luck
cozz