Implantation bleeding?

T

Today is 13dpiui, I’m like clockwork with my period, horrible cramps and I pretty much gush blood when it starts(sorry tmi). I had cramping 9-11dpiui, tonight I went to the toilet and when I wiped I had brown discharge, so put a tampon in, I’ve taken it out an hour later and it’s clean?! This has never happened before. Could this be implantation bleeding?? When could I test if it is?