Could I be pregnant or am I just imagining things??

[FutureMrs2017]

I have a regular period, 28 day cycle, with rarely anything other than mood swings and headaches the 2 or 3 days leading to my period. This month, exactly 1 week ago today, I started having lower abdominal cramps. Mild ones like menstrual cramps, off and on, I was also experiencing some constipation. When I was able to go it would not relieve the cramps. These cramps have been going on for 7 days now and my period isn't due for another 7 days. I have felt a bit nauseous a handful of times over the last couple of days. There hasn't been anything else too weird going on except a pretty bad headache, almost like a migraine, for most of today with some nausea, but I think that was due to the headache. Because I don't usually get PMS cramping, especially not starting 2 weeks in advance (nor do I get cramping or anything during ovulation, I am wondering if I could be pregnant or if I'm so worried about it that my body may think it is. I'm just lzooming for some peace of mind.