Does anyone else have occasional high fevers (102 - 104)....with no known cause?

[Charlean9999]

These fevers will hit me with no warning.  All of a sudden I realize I'm freezing & burning up at the same time, I have such intense shivers that I hurt afterwards.  So far, they have lasted from 6 to 12 hours.  Tylenol doesn't help at all.  The only thing I can do is turn up the heat & wrap up in blankets.  The fever doesn't break like a normal fever, I just slowly stop shivering and start warming up.  It leaves me weak & exhausted for days.  They used to happen several times per week, but since being diagnosed with POTS they've decreased to every few months.  I don't know if the beta blockers are helping or if its the increased liquids I'm drinking.  I also have Sjogren's, lupus, hashimoto's, fibromyalgia, asthma and meniere's, but the fevers started about the same time the other POTS symptoms started.
Thanks!