What Could Increased Sleep, Cold Extremities And Breathing Difficulty Indicate?

My mom is 92 years old. She came down with a drip and cough. Got medicine and that cleared up. She began sleeping alot when she was sick and continues to do so after the cold was long gone. Now she has been sleeping almost 22 out of 24 hours a day for the last 20 days. We took her to the emergency room three times and was admitted inthe hospital for three days. The doctors ran all the test they could and they said all the test came out normal for a 92 year old and they can't see anything wrong with her. She get hot and cold frequently, her fingers on both hands tingle alot, she get out of breath whenshe walks, she is extrememly tired and sleeps 22---23---hours out of 24. Im wondering if her could have a sleep problem not getting into REM creating the tiredness and possible need more oxygen since she appears to be short on breath. What do you recommend?