I would take your son to the doctor. Fasting should be between 70 and 99 and definitely should not be over 140.
I was told that a normal fasting (before eating or 2 hrs after eating) level for kids was between 80 to 180. Both or your kids fall right in that range.
Also, be aware that if you haven't washed your hands (or if the finger you poked on the twin wasn't washed since the last time he ate), you can contaminate the blood glucose strip and it will read higher than it should (even if you don't see anything on your hands).
Always check with your pediatrician though if you have any concerns about your son... the vomiting after eating and stomach pain are serious conditions that may need to be checked out.