The easiest (and absolute worst) way to degrade water params in a cycled FW tank is overfeeding...some do it as beginners, sometimes it happens by mistake...but it will cause issues, sooner rather than laterI think what happened was, while I was cycling the tank to prepare for the shrimp, I put in some fish food. It probably was too much and the tank got overrun with pests/worms. I felt as though the tank was cycled when I added the shrimp. But perhaps they were being killed by sneaky planaria from the substrate. Notice the shrimp are always dead by morning. Because of my efforts to get rid of the planaria, the tank basically un-cycled. *Sigh* I'm going to get some better products and maybe bacteria in a bottle and keep on trying to get this tank balanced out.
ANY time uneaten food sits in a tank for a day or so is a recipe for disaster, in most situations...it's an ammonia "bomb", waiting to go off with just a little bit of time....in most cases, FW fish (or shrimp) DO NOT require daily feeding...IME
At any rate, get the test kit on order, and a good quality conditioner, as suggested above, ASAP
For now, do a large WC, match the tap temp and tank temp as closely as possible...get the dead shrimp out of there, and any uneaten food...treat with the conditioner you have, for now
You DO NOT need bottled bacteria, waste of $, at this point...you need a good test kit, so we can see just how much ammonia is in this tank, and a good conditioner