I'm not sure. I've had some issues with that, but I had an ablation done in Dec so I think I'm still trying to even out. Hope it's nothing too big!

I have no clue. I'm the world's worst about neglecting my health, but I'm going to tell you to go get it checked anyway. 

Are you on birth control of any kind? Isn't there something like break-through bleeding that's common?

I had that for almost a year!

Went to the doctor, and she said no cause for concern.  But still not the most convenient thing!!

It usually isn't anything to be concerned about, just inconvenient.  It can come from being over stressed, from our changing bodies and hormonal changing, if you're on birthcontrol, it can definitely happen due to the fluctuating hormone levels.  Even some rough sex can cause it.