So I was on tri sprintec for a month and then the pharmacy switched me to the generic version, i cant remember the name. I missed two days on the third week, and called my doctor and he said it would be okay to keep taking them. Two days before I was supposed to start taking the placebo pills I started my period, or what I assumed was my period. It lasted about 3 days, like usual, however this time it was rather light and the blood was much darker, and now it is almost about black. Back in december I was experiencing almost the exact same thing, except I wasn't on birth control and had bad cramps throughout what i thought was my period. I ended up having a tubal pregnancy. I have taken two pregnancy tests and both were negative, but I'm still unsure on what this could be. I have a dr appointment in two weeks, but I was hoping to find some answers before then. Thank you!