could I be?

So af showed up but before she shut up I was nauseous and exhausted I'm still exhausted and now for the past two days my lower back has been killing me my lower back never hurts ever and I have a full. But a part of me feels like I could be pregnant I had a dizzy spell's this morning maybe it's wishful thinking maybe it's me not wanting the truth to be mean not pregnant but I just have this weird feeling does anyone know if you can have a full blown period and still be pregnant or has it happened to anyone I know it's possible it just seems weird I haven't taken a pregnancy test but I don't want to take Clomid if I am pregnant any advice