More info would help. For example:

What has your weather been like? What was the source of your plants--purchased or started from seed? How many times have tomatoes been grown in that soil in those raised beds? How much have you watered? Have you fertilized? With what? How often?

Pictures would help lots!

It could be any number of things- root knot nematodes in your soil, one of the many diseases that effect tomatoes, too much water, gophers eating the roots.

Renee