I get severe dizziness and lightheadedness (no spinning) when I get off a car or a bike or when I'm sitting on a toilet commode. Sometimes it just happens on changing head position or when climbing stairs or changing direction while walking. Specially, I can't keep my head tilted in forward direction (moving chin towards chest) for more than a few moments. If I do, I start to get extreme lightheadedness/dizziness and most of the times a jerk to bring back head in normal position. Sometimes when my head is tilted on right or left side, I get a feeling that side's ear is blocked and then a ringing in that ear which slowly fades away over a few moments. This has been happening to me for many months now and I think I've developed anxiety due to it. I get a panic attack if I'm outside my home and start to feel this unbalanced thing. The panic attack worsens the dizziness and in return it worsens the panic. I also have chronic post-nasal drip for almost a decade now, if that could be helpful.