All day tight chest and hard to breathe have seen 12 drs/ tons of tests and no one can find a cause other than small fiber neuropathy/dysautonomia?

Interesting problem: probably either chest wall pain( with tenderness to pressure on areas of junctions between rib and cartilage) ie. costochondritis , can be a virus, lupus, or more compicated disease such as polychndritis. Asthma is commmon and easily documented by simple breathing test. check the oxygen level as well. Lung clots less common but obviously very dangerous and requires fine detail CT lung.