1 week before AF, vaginal throbbing?!

So I am due to start this Sunday and last night and today I felt like I was gonna start. I have a weird throbbing "heavy" feeling in my vagina. Not painful just kinda weird. I took a test this am(early I know) just to see and it came back negative. I'm not too worried about the negative as I am about the early period. Anyone experience this symptom or know what it could be and have gotten a BFP? This last week of waiting is torture. Thanks so much!