This AM we woke up to one of our 2 clowns resting on the sand kind of tipping to the right side....same side we noticed large brownish colored spot under pec fin. She will get up and swim occasionally, in short bursts and then go back to sand. Her breathing is also fast. She has been eating and acting fine until this AM. She has even been more mischievous than usual by exploring the rocks more this past week. She has not been rubbing or scratching. All our water chemistry and temp are in range and stable. We just added the clowns 3 weeks ago as our first set of livestock in our new tank. We have no other fish, just invertebrates. The other clown is fine and no spots are on him. We aren't sure what is wrong in order to help her...any ideas? Thank you!