Suggest Remedy For Nausea

My mother is 86, weighs 117 pounds, is about 5 feet tall, and is in good general health -- or at least has been until recently. For the last 3 weeks she has awakened each morning with nausea She doesn't throw up, but she feels miserable and nothing seems to alleviate the problem except time. By late afternoon, she begins to feel like herself again -- only tired. She went to her primary care physician last week where she saw a PA who prescribed an antinausea medicine and an antidepressent -- neither of which appears to be working. What do you recommend?