Hello, last night I had an unexplained fever. I woke up in the middle …

Hello, last night I had an unexplained fever. I woke up in the middle of the night because I was cold and shivering. (I was under the covers, my husband was next to me without a cover, just in underwear). My body started shaking even more, it felt like a seizure, as if I wasn't freezing but a panic attack happened. I was very scared and frightened my husband, what could this be? It lasted about 10 minutes, then calmed down and fell asleep, in the morning I was very swollen and exhausted.