What could be going on?

So I got my period on the 4th of October it ended the 10th. Didn't bleed or spot for three days. Then on the 13th had intercourse the next day 14th I had brown cm only after I used the bathroom an wiped. On the 15th I had it in my underwear tmi (it was thick n brown). So the 16 I had nothing so I had intercourse that night woke, up the next morning went pee wiped and notice light pink and it's been happening on and off the past two days when I use the bathroom. Kinda cramping last night and today. Do you think it could be implantation? Or is it to soon for that? And maybe something else is going on? Anyone had this problem??