When I was a child, I experienced watching an entity get out of my brother's bed in the middle of the night, and walking through the room, past my bed, and out the door. It was short, and was wearing a hooded cape, so I could not see it's face. It was very scary to me, as at first I thought it was my brother getting out of bed, since he was currently sleeping there. But he was still there sleeping, as the thing got up and began to slowly move.
I was too young to understand this at the time - but I now believe that ALL of us have the power to get rid of these beings. I believe that the scriptures tell us that God gives us the AUTHORITY. But you have to TAKE the authority. You do not need a catholic priest. The most practical thing I can tell you is to constantly be saying this to the demons: "I command you demons to LEAVE NOW in the name of Jesus". But here is the thing - it doesn't work very well unless you really mean it. The authoratative power literally comes out of you if you believe it and mean it with as much as you can.
Every circumstance is different, and so yours might be so serious that you need someone more experienced with this sort of thing. But I would not recommend a catholic priest. You need the help of God's power, not people's religion.
What comes to my mind is a book you definitely need to read. It is biblically based and describes every kind of demon/spirit, and how to get rid of them. Very helpful. It is called "Strongman's His Name... What's His Game?" by Jerry Robeson & Carol Robeson. Highly recommended.
Also, I can connect you with phone numbers of Christians who travel around the country (and world) dealing with these sorts of things. Email me if you want to go this route.