>saw a black dog
>scratches appeared
This is straight out of a superstition from the American south. You're going to start seeing it in real life now, too, following you on a regular basis. There will be more scratches. You'll feel the fur brushing against you randomly, or smell its breath. Nobody else will see the black dog, they'll think you're crazy. If you start finding short black hairs on your clothing or your personal belongings, it means you're probably about to die. This is a curse that you've accidentally walked over. I wish I knew of any way to help you.
Watch your back, anon.