It sounds like you're talking yourself into agoraphobia, and you really don't want to be housebound, right? Did anything happen to trigger such an extreme fear of being sick, especially with things that are rare? At any rate, get into that therapy as soon as possible, your avoidance is beginning to dominate your life. It might also be time to see a psychiatrist if it's really gotten to that point, as mentioned above. Don't wait. Move past this phase of your life. Peace.
Gosh, this sounds like it is really interfering with life for you! I'm not sure what air hunger is. So, I am guessing you have had a routine physical to check your overall health? That's always wise to do and at that time, you speak frankly and openly with your doctor about the anxiety and obsessive thoughts. Perhaps treating the anxiety/ocd could make all much more manageable in your life? My guess is it will. A psychiatrist is good to see and a psychologist to begin talk therapy, learning coping strategies, etc. is very beneficial. This is a treatable disorder and if you can take the steps to get started, your life could significantly improve. I really encourage you to take these steps!