Take a hpt and schedule an appt with your doc!
I'm having a similar problem. According to MyMonthlyCycles (where I track my cycles), I was supposed to have a period on Aug 1st (which means nothing really as I'm very irregular and have only tracked about 3-4 cycles so far). Anyway, Aug 1st and 2nd came and went and nothing. Then I started spotting on Monday (Aug 3rd) and it was light the whole week until today, when there was a bit more but similar in color and consistency to what you described. Now it seems to have gone back to what it was earlier in the week.
Symptoms-wise, I've had the headaches (not like my usual sinus headaches), bloating, very mild cramping, low back pain and I feel a little nauseous after I eat. I've done 2 HPTs and both were negative.
I have no idea if I should consider this a period; since I'm tracking my cycles, should I consider Aug 3rd as CD1? I'm as confused as you, LOL