What Causes Body Chills Along With Dizziness?

My 99 year old mother is always saying she is freezing if the temperature is set at 72. We have a space heater to keep her sitting area warmer. Today the temperature outside went up to 60 and with bright sun felt much hotter. We took the grandkids to a park and my mom (99) came along. She was dressed in velour pants, a warm sweater, and her quilted winter jacket. I kept asking her if she was too hot. She said no, it s cool out, just my face feels a little warm . After 20 minutes she wanted to go home so I put her in the car and came home. When we got inside she suddenly acted like she was feeling terrible, extra dizzy, (she s always dizzy), and like she was going to be sick, though she didn t throw up. I had her drink as much as she could and then she fell asleep. She almost seemed like she was dehydrated and her breathing seemed very labored. She had a stroke 4 years ago that only seemed to take her left peripheral vision, but I m wondering if there is something in that area of the brain also damaged that affects her ability to regulate body temperature or is it something else.