no period- negative tests

Jenna
For the last two months my period has been very light (spotting one day, light the next and the brownish on the third) this month I didn't even get a period. I usually have a 27 day cycle and today is 33 days. I've tested and all come back negative. 
I've been stressed and feeling flu like symptoms- fever, headache dizziness. What's going on??? The unknown is driving me crazy!