Are you sure that the plant isn't starving? How long have you been growing it? It may be time to start feeding it.

I only have one grow under my belt, and it's still flowering 81 days after going 12/12 and I had some similar sounding symptoms around week 3 of veg, as I hadn't fed my plants yet. Added food to water, bingo, happy again. I will add that I was using RO water at the same time and not adding CalMag, so I may have had a Ca deficiency at the same time. When I started feeding I stopped using the RO water (it's for the fishtank anyway).

Good luck.