Nute burn or something else ???

hi all first time i have posted a thread so bare with me, i have a small problem with what might be nutrient burn but im having trouble distinguishing what it is so i was hoping some of you experienced growers might be able to shed some light on what it is' here are some pics
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what you are looking at is a cheese but i'm not sure exactly what strain it is, it is 9" tall 4 weeks old and has just been re-potted this morning that's probably why she's a little droopy looking, but the discolouration started 2 days ago

i have it under a 600w hps 3 feet away

1.2 x 1.2m tent

canopy temps about 25 centigrade

oscillating fan

PH 6.5

growise compost with john innes

i have not given any nutrients yet as i thought there would be enough in the soil, it hadn't even used up the root space in the previous pot, i cant find any mites or anything and i have another ww x bb from fms starting to show the same signs. Any help would be greatly appreciated and thanks.

p.s. does anybody know if it would be smart to top or FIM this cheese...

Pics didn't work. I've seen other people having the same issue, not sure what it is.

sorry i dont know how to fix that they're showing up on my screen