How are you watering? I used to spray my tomato plants with a shower-end hose but had much better results from just sitting the hose on the soil and watering the soil. Less water is lost to evaporation and it also reduces the chance of fungus in the leaves.

I don't know what your set up is like, but ollas are a good way to keep soil moisture constant. Youtube has plenty of advice on homemade ones from terracotta pots. I keep a string anchored and dangling to the bottom of each of mine to avoid drowned bugs and lizards.