I recently purchased a platy (along with a few other fish) from my local fish store. They immediately went into my quarantine tank. The platy developed a small white dot on her caudal fin. Thinking it was ich, I went to my local fish store and purchased some ich medication. By the next day, the spot has grown three times its original size and became shaped like a grain of rice. It has been three days now since the original sighting and there are now two easily-visible pill-shape things on her tail. I can't find anything that fits this description on any forum. It is NOT Ich or anchor worm. And none of the other fish have this... What can this be? Please help!