Hey man. looking at the colour of the leaves which is a really dark green and the leaves clawing down, I would immediately think of a nitrogen toxicity (WAY TOO MUCH nitrogen, not a deficiency at all !!!). I hope you haven't manually fertilized yet, if you havent it is the soil which is way too heavily fertilized (as you said).
I myself would wait it out. Just water pH'd water without nutrients and wait until the nutrients in the soil are used up. It could take a while though, depending on the amount of nutrients in your soil. If you want to be on the absolute safe side or if it gets really bad in the next days / week, you should transplant into a soil that is not or very lightly fertilized and continue watering with plain water until you see a clear change in growth and leaf colour. I dont know how heavy the soil is actually prefertilized so the decision of waiting it out or transplanting immediately is yours ;)
Just keep in mind that cannabis is such a resilient plant (I know RQS genetics, they survive a lot of stress aswell) so your plant is gonna survive. Just give it enough time to recover from the stress :)