Brown discharge 3 weeks before period?

I'm 16. For two days now, I've had brown discharge. My period isn't due till around the 25th or so. I also have frequent headaches which I think are being caused because I suddenly stopped drinking soda.
My boyfriend and I haven't had intercourse, but Sunday night he rubbed his penis onto my vagina. (sorry if this is too much) and he attempted to stick it in but didn't. No, he didn't have a condom on. But he didn't cum and said he didn't see any precum.
Is this a sign of pregnancy? Or is it just my period early?

I'm panicking, I don't want to be pregnant. :/ and I can't get a test because I can't tell my parents there's even a chance without them exploding.