My 11 year old boy
Is 5 foot 11 and wears size 12 men shoes, weighs 250 pounds. What the heck is going on?

Do you mean that he is overweight, or just a big guy for his age? His growth rate is determined by genetics, how ever far it goes back, there must have been someone in your family who had the same build. Start looking at family pictures, it could be a fun project !