wieght gain

My hamster is a teady bear hamster a female and she has gained alot of wieght near her lower stomach in the last 3 days she has changed alot she isnt running on her wheel anymore and she is sleeping alotmore in pacific corners of the cage she was in a cage with a male hampster that died not to long ago im getting worryed i checked some sites i think she might be pregnant but it could also be stress im not sure and im really scared, please help.

[helpmeplz106]

and..was she pregnant?