Brown discharge

So this is the week that my period is supposed to come and yesterday I had some light grey/pinkish discharge and today I have dark brown/reddish discharge. I also have a mild headache, my breasts are sore and mild cramping and lower backache. Does this sound normal to anyone? Or possibly off to anyone? I had dark brown discharge last month too on my period week (for a couple days). I’m scared that it might be implantation bleeding or something. Thanks for any insight that y’all can provide!