So confused this cycle!

Victoria
Any help or info would be great!
So last period was May 7-11, and I'm fairly regular. I track every month and usually have a 33 day cycle. I am anywhere between 29-34. The last 5 months have been exactly 33 days.
I was due for my period June 8....never showed. 
I needed up having cramping, headaches, backaches, nausea, exhaustion.  Took about 8 pregnancy tests, even saw my doctor and requested bloodwork for possible confimation of pregnancy. All came back negative!!!
Has sexy time with hubby June 26, still nothing. Started spotting June 27 and now seem to be getting heavier were I'm now using tampon. So that puts me at cycle day 52 when the spotting started. I've had the worst headache for 2 days now! Grrrr.
Anyone ever experience this? Any ideas what if going on? My dr said all my levels and hormones looks great but wasn't pregnant :(