Strange blood like stuff?!

This is kind of gross, but I would like to ask anyways. I've been on the pill for many years, but recently started a new brand. I haven't had a period in 3 months because when I finish one pill pack, I start a new one the next day to avoid having a period. I've had the same boyfriend for almost 4 years and we have sex.

For the past month, I have had cramping, which feels the same as when I am getting my period. But no period happens since I keep taking my pills. Yesterday and today, in my discharge I notice reddish/brownish streaks in it. It's just clear with reddish squiggles in it. Sorry it's so gross, but I feel like I should ask. Does anyone know what it could be? I'm worried it could be a miscarriage? but I have no idea if I was ever pregnant.