I'm thinking spider mites. Has it been hot and dry where you are? Take a sheet of white paper and hold it under a leaf while you tap the leaf with our other hand. If you see tiny specs on the paper and they are moving, it's most likely spider mites. They are very hard to get rid of, standard pesticides don't get rid of them. You would need a specific miticide, and I don't think it is organic. Néem oil, which is organic could be used if the temps are low enough, but as bad as that plant is infected it would be better to pull it and destroy it and plant a new tomato, if you can find one at a garden center. You also need to check surrounding plants. I'm organic, and because organic substances tend to be milder than chemical ones, you have to do a garden tour every morning to catch issues before they become bad.