2 day period???

I recently experienced a 2 day period which has NEVER happened before (they usually last 5-6 days, no more no less and come like clockwork without taking BC pills). This time it came about 7 days late and seemed normal but stopped dead in its tracks after day 2, so i took a hpt day 3 and it was negative. Day 4 I had light pink spotting that only happened once that whole day and 4 days after that (after working out) there was another light pink spot (only once as well/not from sex) so I really want to know what others think about this. I am 24 and have never been prego before, but I have been feeling a little queesy at times during the day and tired. The sex happened jan8 2013, i took the test feb2 and its now the 7th. How long should I wait to take another?