My son age 15, Acts very inmuture ,has gained alot of weight, eats alot, does not have any signs of going into puberty, no hair, voice change,or any of the normal signs should we have him checked or is this just delayed puberty? Very short for his age 4ft 11 138# he is very active . I guess the rapid weight gain has me most concerned, pluss he still acts like a 10 yr old. He is in 9th grade and has withdrawn from alot of the kids he has grown up with because the are so much ahead of him and he feels he is being left behind. Any suggestions? should we check any medical problems?