well i was the same way but my period it stayed on 2 days an i havent been to the doctor yet because i am scared. But these morning sickness, dizzy lite headed is killing me loss weight, i know what u talkin bout.
I would wait another week or so and test again using first morning urine.
Could be stress. Do you have any of symptoms other then what you said? I would say just wait and see if your period starts.