Hi I Am 36 Day 21 Of My Cycle I

Hi I am 36 day 21 of my cycle I noticed that I have pink discharge after bowel movement. There was some brown spotting for a couple of days then disappeared. I am now on cycle 26 day, 2 days before my period and I had another pink spotting after I wipe again, this is the first time this has happened to me and what's worst I am on my 6th day of suprecur injections for ivf. Note that the initial spotting started before I started my injections. What can be the cause of this.