Possible Tomato Wilt
Leaves are drooping, even though there seems to be enough moisture in the soil.
If you do have enough moisture in your soil, there is a possibility of tomato wilt.
Wilting of tomato plants comes from a soil borne disease. This fungus damages the vessels that are used to transport water to the plant. Thus, they wilt from a lack of water.
Tomato plants with this wilt disease will usually die within just a few days.
At present, there is no treatment for tomato wilt disease. IF this is what you have, you'll need to discard the plants, and be aware, that the disease can stay in the infected soil for several years. A new growing location would have to be used.
Several varieties of tomato plants sold today are resistant of this disease!!
Keep a close eye on them, and hopefully they might just be under some unknown stress and will pull out of it. But if wilting continues, they'll most likely die in a couple of days.