Sounds in the Attic

ok so this happened like 5 minutes ago. wait, first let me tell you about my house. my house has never been haunted before because I have been living in this house for 15 years. so we added onto our house. we constructed my parents room and my sisters room. we have rats in our attic and we have caught many so far. but this time when we added on to our house, we completely blocked off the attic from the rats in my parents and sister's room.

so I was on the computer and I was looking at ghost websites and such and next thing you know I hear a scratching like a rat right above me. I look up and I yell for my sister. it keeps going until she comes in the room and I tell her to listen but no sounds. I tell her that I heard scratching like a rat and she says whatever. so she leaves and the minute she's out of the room I heard 3 large scratches/hits against the ceiling. its been about 10 minutes now and I haven't heard anything yet.

is it my imagination or is something other than rats in our attic clawing their way inside our home? this has happened before but never like this.

Devyn