TDS meters measure everything in the water. I personally don't think they are worth using because you still have to test for other things like GH, pH, ammonia, nitrite, nitrate, etc.
Try doing bigger water changes and see if that helps. Make sure you gravel clean the substrate whenever you do a water change.
Aerate the well water for 30 minutes or more before adding that water to the tank. This will ensure the water has the correct concentration of dissolved gasses in it.
Have lots of plants in the tank for the shrimp to hang out in.
Feed the shrimp regularly (2-3 times a day).