Chills And A High Fever With No Other Symptoms?

Last night in the middle of the night, I became so terribly cold– I was shaking so hard it felt like I was convulsing. I was so cold that I had to get up and put a sweatshirt and sweatpants on. Then, I fell back to sleep for a few hours and woke up again, this time so hot and sweaty, burning up with a fever. I then had to peel my sweatshirt and sweatpants off and go downstairs to take Ibuprofen to make my temperature go down. I couldn’t go back to sleep because I was worried about having a fever and didn’t know what it was from? I don’t have a cold or the flu. This morning, I got up and was fine. I was still very sweaty, but I didn’t have any other symptoms and didn’t feel weak or anything. What could cause someone to just have unexplained chills and a fever?
Lately, I have been very stressed out, and I do have a history of anxiety. This has caused me to sleep very little to none at all most nights. I am wondering if this has anything to do with this? I know fevers signal an infection somewhere in the body. I have a physical at the doctor’s this morning conveniently, so I will ask her about it then. But until then, can anyone else share some insight? Thank you!