spotting on cd 19?

I had an iui in January and it was unsuccessful. my husbands sperm count was too low to do another iui in February so we are putting everything on hold for a bit. we had sex throughout the month but for the first time in almost 2 yrs it was just sex not baby making sex! strangely I woke up last night and when I went to the bathroom and there was blood in the toilet and when I wiped...and even more blood today. not a full period but definitely more the spotting. I'm only cd 19, I usually ovulate between 12-14 and have 28-30 day cycles. af is not due for 10 days! why am I bleeding?