pic #3 is an optical illusion due to grow lights, i think... the swollen interveinal areas i bet are a solid green color despite what teh pictures show? look in normal light if you can.
the paling tip in from bottom up is probablay nitrogen related. as it progresses you do get those necrotic spots later on too.
Pic #4 definitely shows some interveinal and dead spots, which could be Mg-def related.
As others said, pH and concentration of other nutes can all impact availability, even if it is physicall present. Eliminate that stuff, then flip a coin as to how you wantn to attack it.. take notes; see what happens. Learn a bit to make the next time easier. Don't do 1 thing, flip-flop and do a different thing before you see the actual impact of the change. it'll be better for your learning curve in the long-run if you do. When you run around like a chicken with its head cutoff it's hard to figure out what was done that actually worked.