implantation or is my body just cleaning out

So I'm not suppose to start until next week but lately my boobs have been sore and I have had on and off "cramps" if I can even call them that and yesterday I had a light pink milky discharge , could this be implantation or just my body cleaning out? I thought once I saw the discharge I was starting but I didn't so not sure what this is I have never had this happen before.