
Where are you located? Maybe there's a group nearby that can look into this. If this were happening to me, the first things I would do is stock up on Holy water, demand the thing to leave in Christ's name, and get in touch with a clergy person of the faith I practice, or failing that, a Roman Catholic priest, as they have a long history of dealing with these sort of things. I would also contact a good, reputable local paranormal group. That's just me though, and I know my life, beliefs and circumstances, but I don't know either your life, beliefs or circimstances. A quick aside: generally speaking, ghosts and sprirts can not harm you. Period. Insane spirits can cause you to harm yourself out of fear. Demons on the other hand should be feared, rightly so, and that's when a priest or knowledgeable clegy person needs to be brought in. That is assuming, of course, that you are mentally healthy, and I by no means intend to imply otherwise. If you aren't, then a mental health professional is the best solution. If you are, you won't have taken offense to the previous sentence, and you'll begin sorting through my previous suggestions. Another quick aside: Stay away from Ouija boards. If you've ever used one, be sure to impart that information to your investigators and clergy person. Also, if you have used one and still have it, do not destroy it, do not throw it away.
Please keep us informaed on how this works out for you!