Hi..... In 2016 I was taking three powerful antibiotics at the same time for a difficult to treat lung problem. After 4 months of the antibiotics I suddenly lost some hearing in my left ear, and a week later in the right. Also developed vertigo. I was given oral steroids then steroid injections and it did improve my hearing. But only temporarily. Over the course of four years it has gradually gotten worse to the point where there is severe loss in one ear and profound in the other. I have had the course of steroids 3 times and followed up with steroid injections into my ears each time. The last course of both oral and injections did not improve the hearing at all. The vertigo is with me 24/7 and my balance is terrible, have to be so careful not to fall.
Meniere's disease has been ruled out for me. Doctor's are of differing opinions as to whether the original cause was inflammation from an autoimmune disease that I have or from the antibiotics that I took.
Apparently there can be many causes for sudden hearing loss. In your case it seems a real puzzle since you had no underlying health issues. I am glad you jumped on it so quickly and are doing research as well and I hope that everything is only temporary for you. This is a good group to stay connected with and relate to those with similar issues. Good luck to you. Judy

About 4 years ago I had exactly the same thing happen upon awakening. Went to Urgent Care and was told it was a blocked eustation tube and to take Zyrtec. I was going on trip and when I returned it was no better so called an ENT I knew in Oregon. He said he thought I was misdiagnosed and recommended immediate hearing test. After test confirmed a 60% loss in left ear I was put on a course of prednisone and condition did not change. I have age related loss in my right ear so have been fit with what is called a "Cros II Phonak aid in the right ear and left ear a microphone that picks up sound and transfers to right ear. One on one I do fine and have a Com Pilot you can purchase that is like a remote control you wear around your neck. In groups and movies it helps. It can be paired to an Iphone, Ipad and tv. Along with CC it works well for me. My son recently sent me a microphone which I paired to my Ipad and really get a strong sound without having any other enhancement. I am 87 and in very good health. My father had a profound hearing loss as did his father. My mothers hearing was fine up until death. I have had to make a number of accommodations because of hearing loss but the hardest for me is still people speaking up in a group even though I am wearing a yellow button that says please face me and speak up. I have a hearing loss, We have a local hearing Association which has been immeasurably helpful. Weekly peer meetings held by volunteers in a room that is coiled is a wonderful resource to our community. Good luck.