Anxiety can contribute to stomach discomfort...and also can cause things like breathing difficulty and chest pain. I don't think it can cause asthma, but it certainly would not help it...also I don't have asthma but if you have that and anxiety its also possible being anxious about asthma attacks or symptoms...contributes to anxious feelings. But yeah it probably would be a good idea to address all these issues some of it sounds more serious than anything anxiety directly causes.