My boyfriend and I regularly have unprotected sex. This month i got my period three days early, which isn't that unusualy in general but it puts me on a 25 days cycle which is odd for me. Also, it was very very light. After a day it went away completely. Usually i have my period for 5-7 days. The day it went away there was a very small amount of brown discharge on the tampon i was using. After calling my boyfriend freaking out about possibly being pregnant, my period came back very light again. And now less than a day later it is gone. What the heck is going on? I took a pregnancy test today, the day i was supposed to get my period and it reads negative. Could anything else be causing this?