Does the spot on Chloe look like her eggspot?
Do you see the white spot on the betta in the picture? That spot is the ovipositor, or eggspot. It's perfectly normal. If this is what Chloe's spot looks like, then she's not sick at all. But if the spot is a lot bigger than this, then she still may be ill.
When Courtney swims and her body is in the U-shape, does it stay like that for a long time? A lot of bettas do something we like to call a "wiggle" dance, where they bend their bodies back and forth really fast. They do this a lot to gain attention or to ask for food. What color is Courtney? Many darker colored bettas have silvery patches on their gill covers and this is normal but if Courtney's patches look very white and perhaps fuzzy, then that is abnormal.