Deficiency on Fem. Girl Scout Cookies?

What you've got is a vastly underwatered, probably under-fed plant whose lights are far too close to them. If you're only watering "sporadically" you've probably got a lockout of several nutes (I can see both magnesium and probably calcium for two - there may be more) - Plants at this age are usually requiring a lot more water than you report in your diary... so you're not rinsing the salts and excess nutes out which has caused a lockout. When you water, you need to give it enough so that there's at least a 10-20% runoff. And if you only assume your pH is 6.5, that's like filling your car up with gas 3 weeks ago and assuming your car still has enough gas in it for a 200 mile trip today without looking at the gas gauge. Get the lights up at least 18 inches from your plants and then do a flush. For your grow in 3 gallon pots, that means running 9 gallons of water pH'd to 6.2 through each pot.... or at least enough (and more if need be) to get the pH of the runoff to 6.2 which is the "sweet spot" for plants at their age. When they dry out, you can give them nutes but only 1/2 strength for the first feed. Going forward, keep the grow nutes at 1/2 strength as you take your bloom nutes to full strength - in flower, nitrogen is still needed but not at the levels required for veg. And always measure the pH of whatever you're giving her and measure the pH of the runoff - that will tell you what's going on in the soil. Good luck.