Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Emergency care is appropriate for severe breathlessness, fainting, confusion, blue or gray lips, severe chest pain, or rapidly worsening symptoms.
Contact a clinician sooner than planned if symptoms are worsening, begin occurring away from work, interfere with sleep or ordinary activity, or do not respond as expected to prescribed treatment.
Fever with worsening cough, coughing up blood, or new chest pain also needs prompt medical assessment.
Routine follow-up may include reviewing symptoms, checking inhaler technique, repeating spirometry, and discussing whether workplace changes have reduced exposure.
Follow-up is especially useful after a job modification or a period away from dust because lung function and symptoms may change.
The article also says
Bring a list of job duties, safety data, respirator information, and prior workplace lung-test results to appointments when available.
A symptom diary can also be helpful.
Note the date, work area, task, exposure level, symptoms, and whether they improved away from work.
Every sign above is quoted from the sofidex article on Byssinosis. If you are not sure, err upward — it is always reasonable to be checked.