What's wrong with my Juliet tomatos?

[rockyonekc]

Any idea what is causing this? I started the seeds Feb 15th and they germinated and outgrew their 6 cell pack as expected. I have potted them up as they grew using Pro-mix potting soil. They have lived on my deck for the last month moving them inside at night if the temps were forecast to be cooler than low 50F. New growth is wadded up into a tight ball. It's been cloudy and cool, but I've protected them from rains and cold temps.

I thought it might be root bound so I potted up again recently. There was some winding of the roots at the bottom of the previous pot, but nothing unusual.

I have grown hundreds of tomatoes from seeds. I have more than 60 pepper plants right next to the tomatoes doing great. I consider myself a pretty experienced gardener but this one has me perplexed.

Thoughts?