Mine looks the same I was wondering what it is too?

I have the same problem! I cant figure it out. Have you found any answers?

I was told it was due to growing it in a small pot.

I believe I slowed the progress of whatever it is by weekly application of neem oil. There are no visible insects, however. The plants are still alive but growing slowly, with a wilted appearance, many curled leaves, and fruit that never seems to achieve maturity. I should plow them under but figured it would be interesting to see what happens.

You'd think tomato diagnosis would be easy enough, but it is very confounding. I've varied watering, fertilizing, spraying, pruning, and sun-shielding among the 6 plants, with spectacularly ambiguous results. One of them is quite healthy despite everything, the others show no reaction to any of my tests.

I cant even water them to death or dry them out to death. They are sick THEIR WAY.

I don't do anything besides spray with compost tea every three weeks. I would guess either Fusarium wilt or early wilt from the photo, just a guess.

Most folks seem to plant the tomatoes too close together.