Additional info is needed.

So only parts of the foliage are wilting? And doing so when the plants are known to not need water?

If it's total RAPID wilting of the plant with no change in foliage color that's very important to know in terms of figuring out what might be wrong.

Please describe the color changes you see with the leaves.

Are the plants inground or in pots?

Have you grown tomatoes in the same ground, if inground, and had a similar problem before?

Have you sprayed them with anything?

Carolyn