Very strange, indeed “gmarie”. I have no idea what it might have been. But I probably would have done, just what you did. Gotten the Crucifix (and or Rosary) and held it out. I probably would have tossed some holy water at it, too.
About 6-7 years ago… I had a strange experience in our home. It was late evening (past 10:00 p.m.), and everyone was in their rooms for the night. I too, was in my room… and I thought I heard a noise. So I opened my door… (which is at the top of the stairs); I looked down, toward the entry hall… I saw what appeared to be a small, circle of blue light… bobbing around on the floor. It was round, like someone shining a flashlight on the floor. It was moving, and had just turned the corner and seemed like it was about to ascend the stairs.
I got really frightened. And quickly went into my room, closed and locked the door. I knew it couldn’t be a possible burglar… because I had set the alarm… (which would have sounded LOUDLY… if someone had broken in). I waited for a moment… but I didn’t hear anything. I got my courage up… and opened the door again. It was gone.
I knocked on my sister’s door… and asked her if she had been down there. She said… “No”. And I told her what had just happened. It freaked us both out.
Another night, the books in a small bookcase suddenly “blew out” of the shelf… with a loud clatter. Scared me almost to death.
I would suggest, if you haven’t yet had your home blessed by a Catholic priest… maybe you can arrange for that.
I’m not saying the bubble you saw (or the things that happened in my house) were anything evil. But it’s always a GOOD thing to have our homes blessed. And remember… that God loves us. We’re His children. And Our Lady’s children.
Hope this helps. God bless.