Implantation bleeding?

I got my period a week early last night. I've NEVER ever in my life had a problem with spotting in between periods and my periods are regular enough for me to know that they are ALWAYS between 30-35 day cycles. This would have been a 26 day cycle. I'm not under any more stress than I usually am. My diet hasn't changed. I'm DEFINITELY not going through pre-menopause. I'm not on any new medications and I'm not on the pill. I DID have unprotected a few times about a week after my last period. I have an ovulation calender on my phone and if I change my cycle for this month to 26 days the unprotected would have taken place 3 days before ovulation whereas it would have been 1 week and a half if I was on my normal cycle. I'm cramping and it physically feels like a period...but it just seems different and not right to me. Any ideas? and Would it be too early for a pregnancy test?