Downy mildew, whiteflies and blossom end rot....
Okay, so downy mildew and whiteflies both cause the yellow patterning. The best treatment for downy mildew is to rotate where your garden is each year because the fungus persists in the soil. (This is why fungicide didn't work.) Sticky traps are the only thing I've found that works on whiteflies. Make sure that all garden debris is pulled out and cleared away at the end of the season so the flies have fewer places to hide.
Blossom end rot is a calcium deficiency. I noticed that you have egg shells in your garden. That is great except that the roots need to grow through the calcium source to absorb it properly. Crush the shells down to a powder with a food processor or blender so that the calcium can leach out (I wear an N-95 mask for these adventures because breathing egg shell dust isn't good). And then add the shell, blood and bone meals to the root zones (bottom of the planting hole) of your tomatoes next year. You can try and dig it in around the plant now, but there are no easy cures for this year's plants.
Let us know how it goes. I wish I had better news.