hes done that alreadyThe plant will finish if you bud it. I have had the same thing happen to me. Here is a list of things that will cause the symptoms that you had.
1. Cold Temps
2. No Micros
3. Not enough feedings
4. Not enough Light
5. Old Soils that have had to many grows on it without being rejuvenated
6. My city water....it contains a chemical to raise the PH to 7....even if you ph it...it drifts back up in about 3 days (hydro)
That was a list from my experience....
You have a couple solutions though.....
A. Bud it...It would like a little blue light in bud not all oranges....it will make it.
B. Trim It way back, transplant, get rid of the yellow leaves and veg for another 4 weeks.
IMO i would bud it if you have a replacement.
you need daylight6000k cfls during veg stage and 2700 k red light, for bloom, i like to hit them with some daylight6000k the first 3 weeks of flower tho,because there still growing roots and new foilage at that stageim going to go 12/12 tommarow if all goes well my new growth is starting to look alil twisted ima post a pic here soon an ill show you an i plan on getting some cfls dont know the exact kind yet though wanna go with whats best for them