My experience with stuttering is, admittedly, really unusual. However, it's worth mentioning because it sounds like your son's issue is relatively new and intermittent?
My (presumably identical) twin sons were born extremely premature and have had abnormal brain-wave patterns since birth, which suggest a potential seizure disorder. However, neither of them actually HAD a seizure until 1st grade. (The other twin didn't have a seizure until 5th grade.) The one who had the seizure at the younger age had an intermittent stuttering issue that began several months before the seizure. In the weeks before the seizure, it grew increasingly worse until he was so bothered by it that he stopped talking altogether. The twins were already in speech therapy and additional therapies that were tried for the stuttering had no effect whatsoever. In fact, as you have suggested, the focus on the stuttering almost seemed to make it worse, in the sense that my son was more reluctant to TRY talking because everyone was so aware of the stuttering.
I was under extreme pressure from family members to put him in daily speech therapy, or fly him out of state to a "better" hospital, for some sort of intensive treatment, but I had the strong sense that more intense focus on the issue was not the right answer. On the flip side, his therapists were not that concerned about it and seemed to think such speech problems can be par for the course, with a kid who already had speech issues. However, he was being treated for pronunciation issues and I just knew this new development meant something was seriously wrong.
Then he had a grand mal seizure and began taking trileptol. The stuttering improved immediately after the seizure and almost completely vanished after several weeks, as he built up the appropriate level of medication in his system. His speech therapist refused to believe the two were related, although it was just so obvious to me. His neurologist doubted me, but suggested that the stuttering could be tiny "absence" seizures.
I should clarify that what I'm calling "stuttering" was often actually "blocking". Instead of "W-w-what's f-f-for dinner? I h-h-hope it's m-m-m-meatloaf," he might say, "What's for dinner? Ner. Ner. Ner, I hope it's. I hope it's meatloaf." Right before the period when he stopped talking, he might only be able to get through "What's for din-" and would repeat that, or the last few syllables, until he got so frustrated he just wouldn't try to finish what he wanted to say.
Eventually, I took him off the trileptol because it just seemed senseless to medicate a kid for the rest of his life, if he was going to average one seizure per decade. Every few years, he'd go through a period of increasing stuttering or blocking. I'd put him back on the trileptol for a while (in hopes of heading off a seizure). The speech issue would clear up. Eventually, I'd take him back off and he'd be fine for another few years. He's 17 now and hasn't had a problem with speech or seizures, in several years. On occasion, he may say, "What's for dinner? Ner. I hope it's meatloaf," but he doesn't get hung up on it.
His twin also had one grand mal seizure in grade school, but has never stuttered or blocked his speech.
In short, if you find no other explanation, or it gets worse, you might consider an EEG.
Edited by VocalMinority - 10/17/12 at 1:02pm