Hi Soni. Sorry you had to join the Diabetes club, but at least now you know, you can start to take some steps to control it, and will probably feel much healthier when your glucose levels are in the normal range.
Metformin frequently causes gastro side-effects in the early days, but this should ease as your body becomes used to it. I suffered side-effects for about 5/6 days, some people have them for a few weeks,but it's well worth sticking with it if you can because of the benefits. If your not already on the slow release version, ask your Doc if you can change to that, the side-effects should be less severe.
An interesting point about the migraines. I used to suffer with them regularly, at least once a week, since being diagnosed with Diabetes and having my numbers under control, I have only suffered 2 in 6 months.The Doc says it's unlikely to be connected, but I believe it is.
You don't say if you are testing your own blood glucose, if not you need to start doing that immediately, it's the only way to show how you will react to some foods. Most people find it best to go with a low carb diet for keeping numbers in the normal range.
Try to keep reassuring your son that Diabetes is not a death sentence, in fact once diagnosed you can lead a much healthier life. At the education classes they will mention the complications that uncontrolled Diabetes can lead to, only you know your son well enough to know how he might react to that information. If he already knows about the complications, or you know you can reassure him, it would probably be a good idea to take him, a bit more knowledge might reduce his fears.
Hope this helps, Mandy.