Is there something haunting my house?

I live in a big house about 5 years old. My dad just moved out here and every night he can't sleep. Like ever. Hel wake up to a shaking every night at 2 in the morning and sometimes he sees something at my door but I lock it so I haven't. But the other night he went to a hotel and he said he slept like an angle. One time he said he's seen a cat on his night stand and when he turned the light on it it was gone. He's only lived here for about 3 months. I lived hear for 2 and a half years and haven't noticed anything suspicious but it's kinda freaking me out now. :/ is there something wrong? Could it be a ghost?