I was just about to write this, but Neville was the first one:) I agree, @SLP5366, you have a high chance of improvement with time, especially if you still have the same tonal audiogram thresholds and regarding ongoing HBOT.
The dose of prednisone (60mg) was maximum dose (IIRC) and 20 mg is better than nothing, however consider taking 40 mg. You may talk with your ENT about taking steroid during HBOT period for boosting its efficiency, although it’s no guarantee.
Maybe you are lightweight person and amount (mg per kg of body weight) was simply too high. I wonder what means you were sick - infection?