nausea , low sodium , and low hemoglobin

Last winter my mom was diagnosed with slightly raised blood pressure and was given medication. It made her somewhat dizzy at times and she fainted, hitting her chin and the back of her head. She has been experiencing nausea since then and isn't eating much. Blood tests showed low sodium and low hemoglobin. A chest X-ray revealed that she has a slightly enlarged heart. She is tired and weak, maybe due to her lack of appetitie. A little weight loss. Her skin is pale and she seems a little depressed. Although she is an active 83 year old woman, she has recently pulled out of several activities because she doesn't have the energy to participate. Does she need a MRI or CAT scan of her head? What else could this be? She was a pretty healthy woman up to this point.