After thyroidectomy, noisy breathing or stridor is more commonly due to:

Laryngomalacia means dynamic collapse of supraglottic structures during inspiration. It is mainly an infant condition. In adults, an acquired form is possible but rare, usually associated with neurologic disease, trauma, prolonged intubation, or prior airway surgery. Thus, post-thyroidectomy symptoms might be loosely described as “laryngomalacia” only if flexible laryngoscopy actually shows dynamic supraglottic collapse, but first exclude vocal-cord paralysis and edema.

Urgent assessment is needed for stridor, increasing breathlessness, neck swelling, difficulty lying flat, or low oxygen. Flexible laryngoscopy is usually the key test. The medical text notes that bilateral recurrent laryngeal palsy is often seen after thyroidectomy and can produce symptomatic airway compromise. Localization in Clinical Neurology, 8e, p. 4492-4498.