Is my balloon Molly pregnant? Should I be concerned about her scales?

I just got two balloon mollies for my tank, one female one male. This female is noticeably much rounder than the balloon male and she swims the same way my other pregnant mollies did. However I’m concerned about the possibility of dropsy or something because the scales on the top of her head are crusty looking. She doesn’t behave sickly, so any thoughts? Is she pregnant or sick?