Thread: completely stumped

35 and never experienced this before. Always have been pretty regular, with just a day or three variance. However, since starting work with another woman 2.54 years ago, I have moved onto her schedule. Since then, I have been having 21-24 day cycles for months with no spotting. Never have been a "spotter". Suddenly, on last cycle, February 2007, began spotting dark rusty brown 2-3 times a day for 3 days, skipped a day 1/2, then spotted for another 2.5 days. Without warning, then began what looked like a normal period except heavier and much shorther than I am use to (only lasted 2.5 days with only the first being very heavy, bright red and the latter light).

Here is the kicker: the day I started spotting would have been the 21st cycle start date and the day I started with the latter would have marked a 28 day cycle. Using the 21 day cycle, I had sex while fertile but according to the 28 day cycle not fertile. Since slightly before the start of the spotting I have been headachey, nauseous, emotional and hungry. I also suddenly gained 5 lbs in less than a week which is odd as I am an avid exerciser and don't eat carbs. I thought at first I could be pregnant but then I "started" and figured no way, but it was so short. I am finished, it seems, and yet I am still feeling like . I have been reading conflicting thoughts on the probability of same and thought maybe someone might have some thoughts on the matter.

Also, if I am not pregnant, which of the above cycles is the one to go by for the next one? The start of the spotting or the start of the true bleeding??