How do you know when to get a second opinion?

Action's grades have been slipping the last few months....a gradual slide into the world of low B's and now a high C on his progress report which is given mid-six-weeks so we as parents can intervene.  He has been complaining for a while (read months) that he can't hear the teacher.  I have been dismissing him because his reputation for talking in class is well known. 

You can't hear if you are talking. 

If you were quiet, you could hear what the teacher is saying. 

Your problem is not hearing, it's listening.

(Yeah, I know how to lay the smackdown.)

Anyway, after I raked him over the coals for the potential C, he went crying to his sister.  She had a good talk with him and then she came to me to tell me that Action really can't hear.  "Like he CAN'T HEAR the teacher.  It's not an excuse.  He doesn't understand what she is saying.  He can hear sound, but it doesn't make any sense."

me:  So he doesn't understand the concept of the material? 

Skibbie:  NO MOM!  He CAN'T HEAR THE WORDS!!  Like the teacher is talking underwater or through a blanket or something.

me:  Ok.  I'll call the doctor.

One prediatric doctor visit, one pediatric ENT visit and 3 hearing tests later, the results are this:

He can't hear the teacher. 

The pediatric ENT says she can see the scar tissue from the tubes he had when he was a baby.  She doesn't see any fluid.  He doesn't have an ear infection.  The tests confirm that he does have some hearing loss, but it is weird that it has shown up now - why not in kindergarten or the tons of other times they test hearing in school?  Why hasn't he had even 1 ear infection since his tubes fell out at 2.5 years old? 

We talked more about his general health.  He had a bout with shingles this year.  He came home from school with a weird spasm in his neck once this year.  He had a random gushing nose bleed yesterday.

Her solution?  Hmmm.  Come back in a month and see me.  We'll do the hearing test again and see if anything has changed.  If it hasn't gotten better, I'll order a few more tests.  He could have some nerve damage.

What is he supposed to do in the meantime?  I'll write a note to tell the teachers to move him to the front of the class. 

So, I made the appointment and left.  I dropped him at school, after a rockin' cheeseburger on the patio at Willie's Icehouse, with his note to sit in the front of the class, coincidentally where they stick all the kids that misbehave.

Good plan, right?

Now I'm wondering.   Should I get a second opinion?  My worst-case-scenario mind is thinking he has a slow growing tumor pressing on his brain and this hearing loss is the first long-term effect.  My rational mind is thinking it has something to do with the shingles, though none of my internet research supports that line of thinking.  My be-in-denial mind is thinking that if he is somehow faking this, I'm going to kill him, then get him acting lessons. 

Would you get a second opinion?  Or just wait out the month, all the while combing the internet looking for your own solution?