What Do Chills And Discomfort In The Chest Indicate?

My mother lives with me. She is 74 years old. She is complaining of chills with no fever. We took her to ER 2 days ago because of her symptoms including discomfort in her chest. Her primary care doctor asked us to take her to ER. They did X-rays, blood work, EKG, MRI and did not find anything abnormal and sent us home. Her sugars were elevated and the ER doc told us to regulate via diet since she is diabetic. Yesterday and Today, she is again complaining of chills and discomfort. I checked her BP- 128/88 and her sugars are 144. We is under 2 blankets in bed but still uncomfortable. She took the vertigo medication to see if that helps. Waiting to see what happens ....