Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services if you have severe trouble breathing, noisy breathing with distress, blue or grey lips, or sudden voice difficulty with facial drooping, arm weakness, confusion, or trouble understanding speech.
These symptoms are not expected from spasmodic dysphonia and may indicate an airway emergency or stroke.
Seek urgent medical advice for a new voice change accompanied by difficulty swallowing, a neck lump, coughing up blood, unexplained weight loss, or persistent ear or throat pain.
These are not typical features of spasmodic dysphonia and need assessment for another cause.
Arrange a routine medical assessment if you have recurring voice breaks, an unexplained strained or breathy voice, or a voice problem that is not settling.
Persistent voice changes have several possible causes, and a specialist examination can help identify the reason.
The article also says
If you already have spasmodic dysphonia, contact your treatment service if:
Symptoms change in a way that is not typical for you
Swallowing problems continue after an injection
Treatment benefits are becoming shorter or less reliable
Voice difficulties are affecting work, relationships, or emotional wellbeing
You develop tremor or involuntary movements elsewhere
Every sign above is quoted from the sofidex article on Spasmodic dysphonia. If you are not sure, err upward — it is always reasonable to be checked.