Implantation, Period, or Miscarriage ?!

So me and my boyfriend, arent trying to get pregnant but then again were not trying not to get pregnant. I had my period July 14. we had sex atleast every few days unprotected since then, my period is generally every 33 days apart.  I have been feeling very nauses and tired and major headache, and all the "signs", but i havent missed my period yet. my period is due august 16 (tomorrow) but im usually atleast a day or two late sometimes. we were planning on taking a test after the 16th, but two days ago i had a clearish beige clot come out while i was going to the bathroom, and then since that clot came out, ive been having some blood, sometimes ill wipe and itll be clumpy and dark red and then other times ill wipe and there will be just a little tiny bit of pinkish red? i have absolutly no crabs or anything, and im still feeling that tiredness..my period normally by the 2nd day it very heavy and would look like a pool of blood in the toilet, but with the bleeding i have now on day 2 isnt anything like that, it has its times when its kinda alot and clumpy but then theres times whens theres like nothing there, and in my pad it looks brownish with a tint or dark red. what could it be ?