yeah its a tough call... some more and better pics would be helpful...
I had the same problem when i used the organic ferts by fox farms. I advise the use of that stuff with a strain you know and know well. No jumpin around with strains from grow to grow, unless you're Johnny Appleseed with the green thumb to match.
On those outter pics thats burn... definitely. I did the same thing and it looked likie a 3 alarm fire when you walked in.. they were toast to say the least. I switched to GH after that in my soil grow. Absolutely hard as all get out to mess up your plants with it... i like to call it nutes for noobs.
The set of pics under natural light is interesting. I have to ask a few questions because of how leaves are yellowing and where.
What kind of light are you using? Looks like they could be yellowing because they don't enough light or the light you have isn't strong enough.
You get yellowing near the end of your cycle its natural... i'm 2 weeks out and leaves are yellowin as the plant takes nitrogen from the leaves as you begin to flush and not use nutrients.
You also have some spotting that I can see... but its not close enough to tell what it is. I've had that also... but it was from spraying for bugs to close to lights on. it could just as seaily be from a deficiency. Iron or boron or something of the like.
I'd recommend giving as much info as you can when you ask a question.
Example: Nutrients used, pH, and EC, light intensity, day of bloom... blah blah blah. I know you put some of these things in but it just an example.