Need help with sick plant

I have been growing this plant for about 3 weeks now and it started off good but now is looking a little rough. I just started giving it the flora series and cal mag hoping that would help it but it looks like it hasn’t if anyone could give me some advice on how to fix this problem it would really appreciated.

Alot of info missing here so hard to say how to approach, but with what you presented, i'd say lacking magnesium and on the border of too much nitrogen.

Switch to Mega Crop.

stop the calmag and feed organically.