More information needed please: tank size, what else is in it, how long has it been set up. I know what you're doing I presume it's cycled. Ammonia/nitrite/nitrate would be extremely helpful.
What are you feeding, how much and how often? Has anything new (decor/plants/fish) been added to the tank recently?
Both female bettas and female angels are prone to becoming eggbound, but this does not happen overnight. For overnight swelling, I presume you mean abdominal, sounds like dropsy, which is usually bacterial. Are they having difficulty swimming ie could it be swim bladder?
Any chance of a photo?
EDIT: Pleccy's got the right idea - pineconing is dropsy. Any sign of it?