What Causes Chills And Stomach Upset Post Injury Treatment?

My 83 year old mother took a bad fall on black ice onto her left hip and left elbow. She said when she got up she was very dizzy and had a horrible pulled groin muscle. She can walk with the aide of a walker and doesn t have pain (nothing broken thank goodness!), but for the last day or two has felt like she has the chills and a little upset stomach. She was taking Advil every 5 hours for the inflammation, but today (2 days after the fall) she is still having the chills and her stomach is still off . Her other fall symptoms are improving (pulled groin muscle) and walking. Could the fever and upset stomach be some side affect to the fall itself...trauma?