Thanks donna, I looked at the symptoms of iron chlorosis and it seems like it could be my problem. The newestimated leaves are the ones affected and also my plants are in 5gal containers and the soil I used might not have been best suited, so I could see that I might have soil compaction issues. I never got a soil test so I'll have to wait till next year. I'll try to see if I can't find a fix and update this post

Yeah, iron or manganese. Try spraying with these 2, a diluted solution, like 0.2%. Most probably a pH problem, too alkaline, but could also be other causes, like water logging.

Could be magnesium deficiency, too. Iron chlorosis and manganese deficiency usually appear on the youngest leaves first--this doesn't look like that's happening, but it's hard to tell from how those photos are cropped.

The first thing I'd do is give them some epsom salt dissolved in water just to rule Mg deficiency out.

What is your fertilizer routine?

That's not Mg deficiency, 100%.

Look here for a very useful guide on how to spray with what: http://ag.arizona.edu/hydroponictomatoes/nutritio.htm

Note that spraying is better, since if pH is too high, adding it to the soil won't fix much. I would start with iron, and see if in 3-4 days you see color returning to those leaves.

I missed Pcola's comment about newest leaves being affected. If it's newest leaves, then, yes, it's more likely to be Fe or, more rarely, Mn.