Twinges before AF??

My period is due in 4 days and I'm having these kind of twinges in my uterus. They don't feel menstrual related, meaning, that don't feel much like a cramp at all. These twinges vary in pressure but when you feel them your face kind of makes that "ooo" expression but it's not painful, and they're only in 1 spot at a time, whereas a cramp is pretty much all over. PMS has also been very heavy this month, like the symptoms are OD, EXCEPT for my breasts. They're usually unbearable but I can bare them this time lol. The  soreness really only resides at the bottom & sides of my boobs. I know it's all probably nothing but has anyone experienced anything similar this close to AF and what did it turn out to be?