It's awful not to trust your doctor.
I would contact the neurology department at Stony Brook Pediatric Hospital in Setauket. I think that's the closest for you if you are in Sound Beach. There are several offices so chck on the departments at each one so you go to the best place. You can tell your doctor you want a second opinion and workup. If the doctor doesn't immediately agree, you can find another pediatrician, but it's every decent physician would agree to this. Get records sent, and get a hard copy for yourself. Get the images from any testing, not just the report about them. Get this on a disk. Send these ahead (sign what you have to so that everything is forwarded to whatever doctor will be seeing your son) but also take copies of everything to the appointment. My husband sought a 2nd opinion at a major Boston hospital after being seeing in another major trauma center, and you wouldn't believe the nonsense with records being transferred - couldn't open the disk, fax machine wasn't working, primary care physician's office left records for me to pick up during lunch hour but they put them where the interoffice courier picks up to carry documents from one office to the main hospital, and so on. (This was 4 years ago, and I still don't know where those records are - somewhere in the interoffice mail - believe me, I raised a huge stink. But that's another story. My point is, you paid for these tests and MRI and blood work etc., so you own them. Demand them and hand carry them even if they are supposedly sent ahead of time.
Get a 3-ring binder and insert everything in there, along with some plain paper so you can jot down your thoughts and take notes during the exam. If you have a friend or relative who can go with you to either help with your child or be an extra set of ears or the note-taker, great.
You can do this, Mom. It's stressful and it's hard if you're single, but you can do it. Your child has no better advocate than you. Do not apologize to your doctor - it makes you weaken and not stand strong. You are entitled to this. Remember that. Say in a business-like way, "We don't seem to be getting the answers I would like, and I want a second opinion. Please take care of a referral to X hospital, to the first available neurologist."