Good Morning Jasper
I'm no expert mate but I don't think your plants look too bad

The pics of the 'wrinkly' leaves look a little like something that was happening to mine a fortnight or so ago. What really caught my attention was your written description, it sound awfully familiar

Maybe have a look at some of the pics from
When my plants were crap 
I was convinced I had some sort of rot or fungal thing in early stages. As it turned out it may have been some sort of nute deficiency.
Regardless of what it was Essence and the other plantmagic products I'm using has had a really positive effect

My girls have gone nuts now, a beautiful rich green and not a blemish on them

Im sure the bio-silicon has had an effect as well. They had strong stems and branches from training since planting but they are ridiculous now

I was culling males middle of last week and one of them broke my wilki-sword heavy duty pruning scissors

I just stood there looking at them and back at the plant, that seemed to be 'laughing' at me. So I got my secatuers out...

I think I'm going 12/12 today, and I'm doing an essence spray/drench. If I get round to it I will add a couple of fresh photos to my diary to show how they've improved in the last 2 weeks, but to be honest the problem I had was gone 5 days after the first application

don't know if you think your problem is similar, hope you get it sorted though