71 yr old female with sporadic low grade fevers ranging from 99.5 to 101.6 several times a month. doctors cannot find cause. normal or not?

Can be normal: Thermoregulation is complicated. If you've had a through evaluation and nothing abnormal has been found then it is quite possible that your transient fevers are a normal varrience and, though not comfortable, do not pose a health risk.

Diagnostics w/ fever: The key is to get to the doctors or have the tests done WHEN you have the fever- this is the time to 'capture' what is causing the problem. You may be needing a second opinion by this time - and an Infectious Diseases doctor is the type of doc you need. If there are other symptoms that could be clues - be sure to mention those. Hope you can get a diagnosis and some real treatment. Take care.