Girls, hello everyone, we were recently at the hospital with our son f…

Girls, hello everyone, we were recently at the hospital with our son for nine months. The doctors say he's underweight for his height (74 lbs) and weighs 8 kg. They say there's a lack of growth, they prescribed syrup for appetite but he has no problems eating. He eats well three times a day, he eats absolutely everything. He's just very active, crawling since six months old, and at seven months old started walking. Now he walks independently. They say he's early for that, but I don't know what to do, should I put him on a stool and not let him walk? They said if he doesn't improve in a month, they will prescribe different vitamins