popping near sternim from deep breath/shifting sleep positions.

3 things: 1.If I'm lying still on my bed, I shift/deeply breath end pop an area near my stern(e or i?)m. HOW normal is this? 2. If I make a sudden shift in motion (jumping up into the top bunk of my bed or suddenly getting up off a couch/bed) I get real dizzy for a while, almost yet never at the point that I have to sit down or fall like a ragdoll. 3. I'm using a Dsi for research in this site, how do I choose a discussion area to post my topic in?