I'm new at this and suspecting I did something really wrong. At first this was only affecting some of my plants but now it is affecting all of them.
That is a really extreme leaf miner infestation.
This is the wrong time of year in most of FL for tomato plants anyway. Most of us pull them up when they're done in May or June and are just starting new plants now.
When you just have a few leaf miners you can deal with them by removing the infected leaves. I'd pull your plants and start over, assuming you aren't up in Jax or the panhandle. If you're that far north, plan on the spring for starting again.
Whereabouts in FL are you?
Thanks a bunch! I'm in West Melbourne. I'll get some new ones started right away.
Depending on your micro climate you may be pushing it a bit, but with luck you should be okay unless we have an early freeze. Here's a link to the excellent guide to FL vegetable gardening put out by the U of F, which tells you what to plant when in the different parts of the state:
Here is a link that might be useful: IFAS planting guide