Hello,
Two instruments may not be alike and may have standard error of deviation. You should get your temperature checked from a doctor and then check with both the thermometers at home. The one with the closest reading should be used.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.