There is a correlation between asthma and allergy, especially when the allergic state is as severe as yours would appear to be. It is possible, but unlikely, that four doctors, acting independently, would be mistaken in concluding that you do not have asthma, but the validity of that conclusion would depend, of course, on the comprehensiveness of their evaluations. Evaluations that should include a methacholine challenge and pulmonary function tests before and after the administration of a bronchodilator.
A condition that can mimic asthma is Vocal Cord
DysfunctionBasal ganglia dysfunction
Carpal tunnel syndrome
Causes of sexual dysfunction
Chronic fatigue syndrome
Dysfunctional uterine bleeding (dub)
Ear barotrauma
Erection problems
Female sexual dysfunction
Femoral nerve dysfunction
Orgasmic dysfunction
Sciatica (VCD, a functional
disorderAdjustment disorder
Anorexia nervosa
Asperger syndrome
Autism
Autoimmune disorders
Bipolar disorder
Bipolar disorder
Bleeding disorders
Borderline personality disorder
Bulimia
Chronic motor tic disorder of the vocal cords, that even experienced lung doctors can confuse with asthma. That diagnosis can be confirmed by direct examination of the cords, using a fiberoptic laryngoscope, especially if done at a time when you are experiencing symptoms of breath or other respiratory symptoms. It can also be strongly suggested by abnormality of what is called an inspiratory flow volume loop, when pulmonary function tests are performed.
And, yes, anxiety can be associated with chest tightness but anxiety alone is not associated with the production of mucous. That should prompt a search for other diseases of the lungs, for even with a normal chest X-ray, diagnoses for example bronchiectasis and cystic fibrosis) and recurrent aspiration secondary to gastroesophageal reflux, can occur. Such diseases may be obvious on a CT scan of the lungs, when the chest X-ray truly is normal and, unless a diagnosis is established with certainty by other methods, your evaluation should include a CT Scan..
If you have not consulted with a lung specialist (pulmonologist), you should; if you have, but only with one pulmonologist, you should get a second opinion. Your symptoms should be taken most seriously and attempts to establish a diagnosis should not cease, at a minimum, until the above considerations are all addressed.
Good luck