I'm not sure what to tell you here since I've never tried growing tomatoes upside down. I prefer the classic method of growing them straight up in cages in my garden. My guess is that the leaves are being affected by the dripping water. It's probably leaching both fertilizer and minerals from your water on to the plants. Or, you don't say how cold it's been. Tomatoes are very easily chilled and if you've had cold temperatures your plants might have suffered. I just can't tell without seeing them. Again, I recommend growing tomatoes the regular way."