As you can see, the Platy in the picture has no gravid spot. Usually when you have a darker, or brighter colored Platy, you can't see it. However, if you have a lighter colored Platy, you'll be able to see it.
And I'm not sure what you mean by inflammed gills...gill flukes?
Yea somthing where gills are red or somthing like that The chubbier platie looks like mine...Shes a slow swimmer right now and nips at my other fish kinda a mean platie.