Oh man, what did you get yourself into this time ?  :twisted:   Hehe, first thing first.

Relax....take a deep break... your going to be ok

I've been through a similar situation, I'm still debating whether or not what I experienced was real, but I will share my insight.  When I went through my experience with possession I spoke with a witch.  Not in person mind you but it seemed like a much better alternative then a doctor.  What she told me is that these things feed on your negative emotions and bad habits.  Also that I needed to purify my living area.  Look deep inside your self, do you have any mental weaknesses? Addictions, that sort of thing? 

I had many vices myself, and it was something I had to get rid of.  You can "purify" your living area by changing its appearance.  Fresh coat of paint/ect/ect/ect  Some incense helps.