Need some answers... help ladies!

Hello ladies so I got my period October 4th it ended October 10th. The 11th 12th n 13th I had nothing so on the 13th we did the deed that night. On the 14th I had brown spotting but only when I went to the bathroom and wiped. On the 15 I had sorry tmi (thick brown discharge) in my underwear. Ended up doing the deed. On the 16th after I went to the bathroom I had light pink on the toilet paper after I wiped it's been on n off for two days now. Can this be a sign of implantation or would it be to soon? Or could it be something else I also started having cramps yesterday and today as well. Along with back pain. Anyone ever had this happen help?