Prevention causes and treatment

Hi my plants are starting to show signs of nitrogen burn but otherwise healthy plants, within 3 days of curling there has been no improvement nor worsening, just wondered if it could be something other than that, and what I should be doing to reverse this, plants are end of week 3 flowering and are otherwise healthy as I can see, pics of close ups and fuller pictures attached, any help would be great thanks before it’s too late to fix

What are you feeding and how much?

Tri part 70ml 70ml and 150ml, big bud 250ml and c4 200ml, in a 200l tank, week before was exactly same only with 200ml of fruit machine and 200ml of flower bomb PGR, off FM and FB now. Always used this way and never had a problem, would usually use mills A and B as base feed but opted for Tri part this time, and would normally use hades instead of fruit machine, thanks for the reply!

How did they turn out with the FB