I had my 2nd child march 8th 2017 I got

my first period May 3rd and again May 26th, I thought it was over wedesday I had sex Thursday morning and i was bleeding again. Not enough for me to use a tampon it was only when i wiped. Then last night before bed i wiped and it was brown discharge, then this morning bright red blood again when wiping. My daughter will be 3months on the 8th. I use to have regular 28 day cycle periods. So this is new to me? Does anyone know what could be going on? Or is this still my period? I Formula feed