Someone with knowledge of resources in your country may chime in. But as you wait for that.... I'll share that your son sounds like mine with how he visualizes things though mine is only half the age of your son. Your post suggests that he may have a learning disorder. When kids are gifted AND have a learning disorder we call them twice exceptional or 2e.
You might read more in that section of this website to see if you can relate to those posts. From the information you provided, you might also want to research dysgraphia (also known as disorder of written expression) and see if that fits what you are seeing. Generally outside of having a professional evaluation it will be difficult to understand specifically what is happening with your son.
I hope you are able to find answers soon.
