Hot flashes and chills turning into a fever

Since yesterday night, I’ve been freezing cold then hot and sweating. It’s been like this all night and today and I decided to take a nap and I woke up with a fever of 99. I don’t have a cough or runny nose or headache. Just the morning sickness. Should I be worried about the fever? I tried sitting in front of the fan but it hurts and makes me feel more sick so I’m just in a thin robe. It wasn’t even hot out today it was actually pretty windy and nice so I know it’s not the heat.