I feel like you have to be a duck, calm above water, but working very hard underwater. Do everything you possibly can for your child and then, believe in your child. Take an honest look at the grandparents, if there is no problem that you can find genetically, I think it is a matter of coaching, explaining, reinforcing and waiting for maturity. Things can change and improve, say, every three months. Read about men, since you have a boy, who will say that they were 'wild' when they were young, little boys or 'precocious' but are very successful as male adults.
Also, don't worry about people understanding your child from this viewpoint -- by definition, if your child is in a small minority in IQ, how could most people understand? Think of it in terms of another issue like the environment, say, every brilliant scientist says Earth has an environmental problem, that doesn't mean that the vast majority of Earthlings comprehend the extent of the problem, so, the scientists have to 'market' the issue in a way that the average person can understand.
Try to get by in the school setting. If it feels awful, then try home or cyber schooling until the child matures. You really want to do what is best to make the situation positive.
Hope it helps. Good luck. You really aren't alone. Keep reading and researching and you'll realize people have many things in common. For one thing, you are a caring and sensitive parent who is on top of the situation. If you are a gifted person, you are probably very hard on yourself and very sensitive to the situation. Just stay on it. Make sure everyone gets as much rest as possible. Also, sometimes it helps to make sure the diet is very clean. Sometimes, it is the little details that can make a difference.
Also, try to find any triggers. Gifted kids can often express in great detail why they are in conflict. Perhaps your child feels provoked and then the intense, gifted response is the one getting attention and then your child is in trouble.
