Period or implantation? Brownish discharge and it is a little bit heavy

Hello! I had sex in my fertile window, which was last tuesday. Yesterday (I'm was eight days away from my period) I had brownish discharge but now this morning i'm having red/dark pink watery dishcarge. It's a little heavy too. I know many sites say that spotting is more common but I also came across a few sites with people having heavier implantation also. Its definitely not like my usual periods and the cramping is off and on and really not that bad (which is also differnt from the norm). I seem to have a lot of reasons to belive it is truly implantation with the timing and differences but I'd love to see what other people think and have gone through. Please help! Thank you lovlies- Also: It is CD 22 for me today and I have been expiriencing symptoms. I have a low appitite due to my medication but i've actually been pretty hungry. I'm also noticing alot of back pain and still mild cramping, not to mention naesea. I just know I tend to over anylize so i'm afraid i could be over thinking