The green mean machine - Hulkberry auto

Not changing the ties any longer...trying to get her to fill the space as much as possible. The underfeeding on weeks 2 through 4 made her much smaller than I expected at this point. Still, I'm happy at this stretching point. She continues to grow like she wants to prove something!! I am hyper happy that she has not changed gears into full flower yet, and is still in a kind of very early flowering stage, giving me as much time as possible to make things right. Yes, it will take longer overall, but I find that comforting. Lights at 100W. Day 47, she seems to be growing faster (I finished the previous batch of CocoA:CocoB 1:1.2 and yesterday already gave her a 1:1.4, and she seems to be thriving.) HELP! At day 49 something happened! Plant suddenly wilted, all new growth is just drooping, without any feed, anything being done! I always fertigate 2x per day, last 7 days I give 900mL per fertigation. I never ran into overwatering in coco+perlite! Plant is on a raised saucer with holes. Fertigation today was done with a mix I prepared yesterday and I did not notice any problems during the whole day, until now. She actually seemed to be growing, it seemed like she grew almost 3cm from morning to about 17h Is this Pythium? Is my plant dying, suddenly? What should I do? Flush with a "lowish EC"? This is really troubling! Checking the bottom of the fabric pot there are all these root tips coming off of it and they are all looking fine. Through the side of the pot, and digging a little bit I could not discern any bad smell from soil.