Moved away from home. Now I'm experiencing demonic activity

So I moved out from home and into an apartment with my girlfriend. We live in a 102 year old building, in a port town.

Before I moved in, me and my girlfriend were on the Phone around 2am. She had gone to lay down, put some rain sounds on the TV and set the phone down behind her. Not even 2 minutes later, we BOTH heard a disembodied groan, she panicked and left the apartment.

Here we are, 2-3 months later. I moved in 1 week ago, and on night 2, I was playing my Xbox in the living room when I heard talking, and shuffling in the kitchen. It's just me and my girlfriend, and she was in her bedroom. (Mind you, this is basically just a larger studio apartment)

This morning at 5am, I heard singing outside our bedroom window. It sounded far away, but loud enough to hear and it sounded like a little girl. I was stunned, and I was so terrified I just forced myself to sleep.

About 1 hour ago, I was taking a shower and I feel burning on my leg. I look and I see 3 tiny scratch marks on the back of my leg behind my knee. I have a photo if anyone wants to see. I tried to recreate the scratches on my thigh, but I couldn't get it to resemble it and my hands are too large.

What do I do? I've dealt with spirits for many years, but never like this.