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 for difficulty breathing, collapse, severe chest pain, or swelling of the tongue or throat.
Contact your surgical team promptly for increasing pain, worsening redness, fever, foul-smelling drainage, persistent vomiting, dizziness that is not settling, or hearing that suddenly worsens after starting to improve.
Seek urgent medical assessment for new weakness or drooping on one side of the face, severe spinning dizziness, or sudden major hearing loss.
Report them sooner if severe, worsening, or different from the instructions you received.
The article also says
Mild blood-stained drainage, fullness, reduced hearing from packing, and temporary taste changes can occur.
Every sign above is quoted from the sofidex article on Fusion of the ear bones. If you are not sure, err upward — it is always reasonable to be checked.