Dude tbh, to diagnose that you're gonna need more info on your grow... It's like going to the doctors and telling him somethings wrong but you don't have any info on yourself. Next time maybe just put some info such as ph, grow medium, strain, temps, etc etc etc...
Anyways, from my inexperienced eye, it looks like it MIGHT be iron deficient?
I'm not sure if you should try to flush it at this point, but I think you might wanna stop feeding it until you find out what's wrong with the plant. Might lock it out more