What Causes Brown Vaginal Spotting Between Periods?

Hi. I m having brown spotting between my period, kind of during ovulation. There are also large dark brown/black clots. It s the second month it s been like this. When I m on my period it is normal, like usual. Also, my discharge increases right before the spotting happens. Other than that, it is normal, no smell, clear. I took emergency contraception last month. I don t think it is because of that, though. The last time I had sexual intercourse (a month ago) it was not painful unless he went very deep, which was uncomfortable but not painful (he is well endowed. Also, I have been under very heavy amounts of stress, and I have severe health anxiety (hypochondria, which doesn t help because it makes me think I m severely ill or dying). Could the stress and anxiety be affecting my hormones?