zinc or sulphur?

or something else? this just showed up 2 days ago and i've never seen anything like it happen so quick. this is a sharksbreath clone, i've already harvested the mom (mom was fed the same stuff). been flowering for about 2 weeks. she was vegged for 3 weels in a mix of ocean forest, happy frog and perlite with a smidge of liquid lime on the first watering and was only fed water the rest of veg. she got one feeding of half strength jack's bloom 2 weeks ago when i put her in the room. the ph is on point at about 6, not so acidic as to cause something like this...it's just the one branch, too.

whats the ph of the runoff.
RO water or tap?
what are the temp's / humidty in the area of the effected plant?

Normally id say it looks more like a mag def then anything definitally not sulfer... posibally zinc. but Parts affected by a zinc deficiency are young leaves and petioles

runoff is about 5.8, soil claims to be around 6.3. i use tap water but let it sit overnite in a 5 gal bucket in the room. it comes out of the tap exactly at 7 and i don't adjust it unless i mixed nutes in. temps have been fairly chilly but not alarming. range from 60f-to about 75, never more than a 6 degree flux in a given day. humidity hovers around 35. messed up part is there are 3 other plants of 2 separate strains in there at different stages of flowering that have been in the same conditions, same food and they are fine. the mother plant of this clone was a crazy mutant thing but never showed anything like this. it was just ugly is all. you can't really tell in the pic but the bud looks fucking albino it's so light. at first i thought light bleaching but it doesn't look like any light bleach pics i've seen, and it's only a 400w hps...