How many gallons is the tank, plus you should never do a complete water change as you send fish into shock, through altering the stats.
Not the writer of this information below.
Shimmies
Symptoms:
This disease is named for the curious behavior seen in afflicted fish. Fish will swim with an odd, shimmying movement of the body. If left untreated, the afflicted fish will become unable to swim and will sit on the bottom, listlessly shimmying. This disease affects mostly livebearers, and particularly Mollies.
Cause:
Cause unkown but may be due to a variety of numerous pathogens, including protozoan, bacterial, and fungal.
Treatment:
Isolate the fish in a hospital tank and increase the temperature to 85?F (27?C). Treat with a broad spectrum antibiotic. Also ensure that the water chemistry is within acceptable ranges. Livebearers' should always be kept in water that has a pH of 7.8 - 8.3 and a hardness of 15?DH+.
