A lot of time these bruises come from just walking around your house and bumping into a counter or similar item. It it isn't raised and minimal pain I would put it here.
I Have Found An Abnormal Dark Purple Bruise In My Lower Abdominal Area With No Pain, What Could It Be?
You probably just bumped something and don't remember it, I do that all the time. Hate it too.
Instant purple bruise