My last period started on the 4th of April but 2 days ago (on day 18 i think) i started getting a medium brown very light 'period' its lasted for 2 and a half days and is so light i don't need to use anything. It is not a period as it has stayed the same in colour and not got any heavier. Also i have no symptoms, no cramps, pmt, bloating etc. I'm a little worried i may have caught an std but don't see how that is possible as i am in a committed long term relationship. Any advice please.