Hot Flashes... Early pregnancy symptom or PMS symptom?

I've been having hot flashes lately.. Like all day since the night before last night. Usually I could sleep bundled up in my blankets but now I can't stand it and feel like I need to be sleeping with a light sheet instead. Could this be a early pregnancy symptom since I am trying to conceive or more of a PMS symptom? My period is due Wednesday so I'm not really sure... I have read online that it could be a pregnancy symptom but it also could be PMS... Like a 50/50 chance just about.