Can Tinnitus And Hyperacusis Caused By A Water Balloon Injury To The Ear Heal Over Time?

Water balloon hit left ear. Painful at the time but now even 3 months later (and 2 ENT dr visits) he still has ringing in his ears, highly sensitive to sounds. They say ear drum looks fine, no infection. Likely damage to inner ear, tinnitus, hyperacusis, etc? Dr. won t prescribe antibiotics or steroid (we just thought worth a try). Plan to have an MRI which is fine. Looking for a glimpse of hope that not permanent damage. How long does it take to heal? Some days the ringing and pain is so bad. Really affecting his daily life and enjoyment. Can they do any type of surgery to relieve something? Does the nerves heal? Thank you.