B.P.
I am having similar issues with my 2 yr old. You ned to start with apediatric audiologist, not an ENT. The audiologist will test all tones and leves of tones to find out exactly where the issue is. I may be as simple as fluidin the tubes blocking the sound getting to the hairs in the ears that reflect the sound back. Clear as mud?
What area are you in? We saw a great audiologist in Galv. at UTMB. LMK if you need the #.