Not sure what to expect lol??? HELP!

AF is almost due ( don't want her ) I took a yet this morning is was negative just a dollar test but I literally feel like my back is gonna fall off?! Is this a symptom or pregnancy I am also cramping it's not period cramps either its kind of dull I've had cramps for a few days now and a regular 27 day cycle so AF will be here Thursday! But I'm not sure if this is a sign of pregnancy or not all I know is I need a warm bath because my lower back is so achey and I feel like my uterus is being squeezed haha!