It's not a deficiency, so take your grow shop's advice with a heap of salt from now on.
What I see is N toxicity. It looks like a watering issue, but my guess is the roots are pissed off and not behaving. I'm sure you've since watered, but I'd run it on the drier side, and only give water until she bounces back.
Since your other plants are fine, it just means these genetics from Mephisto have different requirements. Mephisto is pretty well-liked so I wouldn't knock his gear over one plant you're not familiar with.