The clue to the mystery is the rain and humid weather and the fact that the yellowing started from the bottom up. I suspect your tomatoes are suffering from a Fusarium Wilt  disease and there is no cure for this fungal infection.  Remove all infected leaves and allow the fruit to remain to see if it will mature. Pick all tomatoes at the first sign of rot or brown spots on any of the immature tomatoes. You may be able to ripen a few indoors and out of the weather.  In the future plant Fusarium resistant tomato varieties such as Better Boy, Better  Girl, Homestead, Marion and Super Sonic tomatoes. Some varieties have the letter "F" on the plant tag to indicate that they are Fusarium disease resistant. In rainy climates growing tomatoes under the eave of a building or some other location that keeps the foliage dry will help them resist disease. Keep growing, Marianne Binetti