It Wasn't The Dog, So What Was It?

I've been reading stories on this site for a while but this is my first time submitting one. First of all, let me give you a little background information. I am 24 and I recently (last month) moved in with my sister and nephew after having lost my job due to a knee injury. My room is on the second floor, down a hallway at the back of the house. We're right on the Baltimore County/City line, and the house is relatively old, built in the mid-1800's I'm told. We live with a number of animals; one dog, one cat, four fish, and seven guinea pigs. My sister works, and my nephew is school-aged, so I primarily care for the animals when I'm home during the day. I don't mind except for the fact that the dog (she's a Boston Terrier) has an obnoxious habit of clawing at my door when she gets bored. I think she does it because she can smell the guinea pigs, four of which live in the room with me. As a precaution I always keep my door shut whether I'm in the room or not.

Yesterday I woke up at 7:30 and started my daily chore list which includes putting both the dog and the cat outside. I usually let them back in an hour or so later, depending on the weather. Anyway, both animals had gone out, and I was upstairs in my room drinking coffee (also part of the normal routine) when I heard the dog scratching furiously at my door, which was shut as usual. I started to get irritated at the noise and the intensity of the scratching, as both were increasing, so I jumped up and threw open the door, intending to scold the dog. She was, of course, not there. This is when I realized that she was still outside. I made a thorough search of the house, every room, under the beds, behind the couch, looking for either the dog or the cat, convinced one of them must have gotten in somehow. There was no sign of either animal anywhere in the house. I went outside next, and the dog was on her leash just as I'd left her. When I called for the cat it took a few minutes but he came running from the direction of our neighbor's home (he likes to mess with their cat every chance he gets) so I was now certain that neither animal had been in the house. This left me quite perplexed, as the scratching had been clear as day, and as I mentioned it was intense, not the type of sound one might imagine. I also knew that the guinea pigs could not be responsible, as they were in their cages, and it certainly wasn't the fish, for obvious reasons.

I was trying to think of a logical explanation, as I am generally a pretty skeptical person, when I recalled something my nephew said to me a few weeks ago. My nephew is five and quite imaginative, but he's not given to making up tall tales for attention. Anyway, he told me very seriously (almost like he was afraid he'd get in trouble) that he had seen something with red eyes under his bed. At the time I found it strange, because the dog sleeps in my sister's room, no exceptions, and the cat sleeps on the screened-in front porch, but I told him it was probably just a nightmare. Now I'm not so sure.

I am a skeptic, as I stated above, and while I'm not sure how to label these experiences I have no problem admitting that I don't have an explanation. It makes me wonder though... Is there something other than our pets in the house with us? I haven't discussed it with my sister yet, as she is an even bigger skeptic than myself, so I figured I'd see if anyone out there has any ideas.