What Causes Intermittent Brownish Discharge And Fever?

I'm tracking my BBT and cervical mucus as my husband and I are trying to get pregnant. My temperature has been up for 10 days and 2 days ago during/after sex I had some bleeding (brownish in colour). Next morning my temp dipped so thought my period had come but next day my temp was back up and had no more bleeding since just some brownish discharge when go to the toilet. Could you tell me what this could mean?