Possibly parallel-- I've had a feeling for a long time that something bad was about to happen. Relatively recently, I've come to believe that this isn't necessarily an accurate intuition about the world, it's muscle tightness in my abdomen. It's probably part of a larger pattern, since just letting go in the area where I feel it doesn't make much difference.

I believe that patterns of muscle tension and emotions are related and tend to maintain each other.

It's extremely unlikely that everyone is more competent than you at everything. If nothing else, your writing is better than that of a high proportion of people on the internet. Also, a lot of people have painful mental habits and have no idea that they have a problem.

More generally, you could explore the idea of everyone being more competent than you at everything. Is there evidence for this? Evidence against it? Is it likely that you're at the bottom of ability at everything?

This sounds to me like something worth taking to a therapist, bearing in mind that you may have to try more than one therapist to find one that's a good fit.

I believe there's strong psychological effect which can create that impression-- growing up around people who expect you to be incompetent. Now that I think about it, there may be genetic vulnerability involved, too.

Possibly worth exploring: free monthly Feldenkrais exercise-- this are patterns of gentle movement which produce deep relaxation and easier movement. The reason I think you can get some evidence about your situation by trying Feldenkrais is that, if you find your belief about other people being more competent at everything goes away, even briefly, than you have some evidence that the belief is habitual.