Thank you for your query.
1. The most common cause for this is acidity,stress
or acid reflux
leading to a vasovagal attack. In most cases, this is harmless. However it must be investigated to prevent it from happening again.
2. The Ear is supplied by many nerves that also supply many other areas of the body such as the face, tongue , teeth, throat, heart and stomach.
3. Get your Pure Tone Audiograms (PTA)and Tympanogram (Impedance Audiogram or I/A) done since you had decreased hearing. Get your ECG and Chest X-ray done.
4. You should see a physician.