I would like to point out that in livebearers, shimmying paired with fin rot can be caused by columnaris. However, if they aren't basically dead right now, it is more likely that your fish have some kind of severe bacterial infection, manifesting itself both internally and externally. I would suggest testing all of your water conditions, and correcting any that are off. Doing a water change and adding salt will likely improve the tank conditions, and salt kills many freshwater bacteria. In addition, you'll want to seek out a strong, broad-spectrum antibiotic such as tetracyclene that can deal with both the fin rot and possible internal infections simultaneously. Feeding anti-parasitic and anti-biotic foods (Jungle makes them) can boost recovery time as well, though you'd need to ground the pellets for them because they are just so darn small.
If people ask for parameters, there is a reason, so please just trust us and give us the requested information. I would not wait until tomorrow for the water change, or the parameter test, honestly; I would do both today, with aquarium salt, and begin treatment ASAP. The longer the fish are in poor water conditions, the more the condition will advance.
It'd also be great to know tank size, tank temp, if it is cycled or not, the frequency and type of water changes, etc. as all of these things can help in diagnoses. Different diseases and parasites have different conditions that they breed in, and different pathology. The more info we have, the better.