Watermelon Sugar High

So there's a few thing here. I'm a new grower but good at troubleshooting so take all this with a grain of salt. 1 your Temps seem really low to me. I stay around 24 to 26° and I don't go below 19° at night. 11 seems very low to me. Could be why you have pink stems....could also be Genetics and a few other. 2 the curling leaves is typically nitrogen toxicity, over/under watering, light/heat stress So what I would do is this. I would raise my Temps to approx 24°C and night time say 18-19°C. Keep your RH in the 40s. See how the plant recovers. Also check the PH of your soil to make sure your nute uptake is not affected. And lastly make sure your not feeding Nitrogen, as this late in flower she needs P and K. These are the first steps I would take. See how she responds and go from there. And as others have said to me, DONT PANIC. Cheers🌲🌬️