weird period?

So my period is normally pretty standard. I get it for around 5 days and it's not too heavy and I don't get horrible pains. But my last two cycles have been extremely weird, I should start by saying I don't have sex. As I'm still a virgin and I'm not on any birth control my last two periods have only been dark brown blood and that's all (sorry it's very tmi) 🤷🏽‍♀️ and I'm not sure if I should go to the doctor or not?