Sick Pregnant guppy

[Amba]

My pregnant guppy has started acting strange today. She is sitting on the bottom of the tank, she occasionally swims to the top, and stays in pretty much the same place, very inactive, then goes and sits back down the bottom in the corner. Please Help!

 

[Amba]

The guppy is in a 34L tank along with two other female guppies and a Loach. Have had her for a few weeks. Newly added to the tank were two plants, wisteria and something else though I am unsure what it is called...

 

[Fishy McFishyPants]

That could just be the pregnancy. How pregnant is it????

 

[Amba]

Um, very? She looks like she is about to burst? She has a very large and squared stomach, but has looked like that for a week now..