Cramping?

My period usually always comes on the 19th or 20th of every month. I have had mild cramping for about a week now, I've just assumed my period is coming. But it still has not come. The cramping I am having is not like cramps I get when my cycle is coming(if that makes sense). Usually my cramps are very heavy more so and the pain is kind of unbearable. But these cramps come and go and they don't really bother me... also when they go away it's more like I have a soreness when I move around, like it just feels sore and strange. Anyone ever experienced this?