Second son waiting on diagnosis and starting having strange symptom this week

So my 5 year old middle son has Chiari 1 and had decompression surgery in dec 2011. My 3 year old started having swallowing problems and his pediatrician agreed to get him tested. His MRI is scheduled in August. However, in the past week he has started studdering real bad. He had never done that before, ever! It has got much worse as the week has went on. Tonight he complained with the back of his neck hurting. My 5 year old did not have these symptoms and I know the symptoms can vary, but could studdering be one? It is so difficult to tell with Ian. He is only three but his pain threshold is crazy. Where my other boys would have screamed with an injury he just rubs it and goes on. That can be a good thing but it is hard to tell if something is serious.

I guess you can just wait until the MRI but maybe you can ask if you can get his test moved up just to ease your mind. My son started studdering at three but they told me it was a normal thing since he was very advanced he just wanted to say alot and couldnt get it out fast enough. So hopefully it is like that. Well I hope you get all your answers :)