I hope my post won't panic you but I lost nearly all of my hearing (can't hear unless over 80 decibels) in my right ear at age 25.
I was treated with steroids but my hearing never came back in that ear. But I think if I was you I'd get it checked and treated with steroids immediately. Most people regain their hearing after steroids.
I do know that my case is so unusual that the neuros regularly "forget" about my hearing loss when assessing me as they think it's so rare in a person with MS. I remember seeing a statistic saying it was 1:100,000 people with MS (gee I'm SO special
). Also there is a strong history of one-sided deafness - my granny, my great aunt, my great grandmother were all deaf in their right ear like me. So maybe it's not just MS in my case. I did get a good second opinion from an ear consultant (can't remember the name for one) and they also felt it was due to my MS but could not be certain.
Good luck and hope your hearing comes back very soon.