I had a pulsox reading at home of 36bpm.went to dr. had a reading of 40bpm on there's, i was hooked to ekg same time showing 100 bpm. i have bad pvc's?

Inaccurate: The readings sound spurious. If you have faintness or passing out spells, you may truly have a slow heart rate but, if you're feeling ok, the pulse ox may not be correct. Depending on the type you have, there is a waveform or possibly an led that alerts the user to inaccuracy. Not sure what you mean by "bad pvcs". Everyone has some. If yours are extreme, you should see an electrophysiologist.

Could be: Pulse oximeters are notoriously bad at determining heart rate when frequent extra beats (or in many cases even an irregular beat) are present. The ekg is the definitive answer. Your condition, based on your age and gender is most likely either premature atrial or ventricular contractions, but without seeing the ekg, i can't say for sure.