The skin folds are interesting. Has she (definitely a girl) lost weight recently?

It kind of reminds me of Telmatobius culeus, another genus of aquatic frogs. This species is large and doesn't leave the water. It uses it's skin for cutaneous respiration, whereas clawed frogs don't.

She may have had a mild case of bloat that she recovered from on her own. Just enough to stretch her skin?

If she isn't showing any other symptoms, I would watch her closely. If she goes off food, loses weight, or starts swimming strangely, I would take her to a good herp vet.

In the mean time, try to get the ammonia down to zero. Nitrites and nitrates look good. Some pothos ivy rooted in the aquarium can help with the ammonia and the small amount of nitrates, but your nitrates are well within the acceptable levels.