AF early or spotting...

So I got some brown (old blood) spotting on Wednesday the 7th. I wasn't due for AF till Sunday the 11th. I did have what I thought was a period but it was a lot lighter than anything I have ever had. Now today monday the 12th I still have spotting (brown when I go to bathroom and wipe). When I check cervix this morning I had some dark brown blood again. Took a pregnancy test Friday the 9th and it was negative. I'm cramping now, I'm so confused this month. Any input?