Heather,
By your thinking about it too much, you are giving those feelings power and making it worse. First you have to face head on that this is only a "feeling" It won't hurt you. Then, you have to ACCEPT that it is nothing more than a feeling. Don't examine it, don't give it a second thought. Once you've accepted that, try not to listen in on the feeling, just "float past it" In doing this, over time, you will notice it less and less, until it is gone.
The trouble with those of us who have strange feelings like this is that our minds are so sensative to our bodies and our surroundings. We have to try to de-sensatise ourselves and not read into our feelings. Just accept and float past them as though things are just fine.
I see that you are new to the board, and would HIGHLY recommend that you read Dr. Claire Weekes books "Hope and Help for your Nerves" and "Peace from Nervous Suffering" They will really help you to understand and get through much of what you are going through. They are pretty easy reading, short and to the point!
Hope you are feeling much better soon, and try not to worry, thing WILL get better.
Kim