It sounds like classic symptoms but I wouldn't get super worried about it until a doctors appointment...after all he is a child, and in my experiance all children are moody and, quite frankly, crazy
That being said if you are really worried you can go to the supermarket and pick up a meter (we use Bayer Contour), it comes with a meter, lancet, and 10 test strips. You can test him when he first wakes up in the morning to see what is fasting numbers are, and you can check him a few times before and after he eats.
Also, what we've recently discovered is the Bayer A1CNOW(http://www.walmart.com/ip/Bayer-A1CN...t-Kit/11332213
). We recently took Billy to one of his Dr. appointments and his A1c seemed "off" so we bought one of these, just for a "second opinoin". In 5 minutes we had the exact number that showed up at the Dr's office.
If you wanted to go those routes getting either one would be fine. The Bayer meter will test what the blood sugar is in that moment. The A1cNow tests average blood glucose over the last 3 months. Normal A1c is anything below 6.0
For an unofficial diagnosis the A1cNow would be best (aside from going to the Dr. of course).
Having said that, if you tested his blood sugar and it came bast a higher number, call the doctor, tell them what you the symptoms and tell them the number and chances are they'll get you in right away.
And remember, relax. He's probably just being a normal 5 year old