brown/pink discharge off/on

I have no idea in earth what is going on! 
Suppose to start period on Thursday, with very very mild brown spotting that would stop and start.
Friday woke up with nothing, then started spotting brown and pink somewhat throughout the day. I put a tampon in at bedtime bc I thought maybe my period would start. 
Saturday morning the tip of the tampon is barely covered in brown/pink nastiness, took it out & now even when I wipe NOTHING! 
What on earth is going on? I took a HPT just bc I thought this was weird & its negative?? 
Anyone ever had this happen? So unlike me!