I have several tomato plants that are exhibiting odd wilting behavior. I noticed someone else was experiencing the same problem but there was no follow up. And I thought I'd ask the experts :D

I have two romas in containers (5-10 gallon buckets). The plants themselves are only about three ft tall so they should have enough root room (right??). I noticed maybe about two days ago that they seemed wilted. So I watered thoroughly and moved them from direct sunlight. I thought that since it was rather sunny and humid the past few days, that might be the issue. However, now my cherry tomato (2 of 3 in ground) plants are doing the same. Again, lots of water and added some tomato plant food.

All the tomato plants affected do have young tomatoes (maybe about a week now) on them. I haven't noticed any bugs or slugs on them. They just seem...wilted. Any and all advice would be greatly appreciated. We planted 'maters last yr and yielded a lot of green leaves but no fruit. So this year, we're looking forward to getting something.