Sometimes tinnitus can occur without any cause. Please get a PURE TONE AUDIOMETRY done. It will give a better understanding.
Meanwhile you can take tab Tinzit one tablet every day for a month along with cap neurobion once a day for a month.
Next Steps
Get a Pure tone Audiometry done and meet an ENT specialist.
Health Tips
try and ignore the sound as much as possible. you can listen to soft music to fall asleep.