The short answer to your question is yes, the hemoglobin of 6.8 is extremely low, so it is important that your son be seen by a specialist. This does represent a serious problem, but the problem may or may not be easily fixable. In somebody your son's age, I would be first worried about potential iron deficiency. If your son is a milk drinker and he gets most of his calories from cows milk, this can result in iron deficiency anemia
which can become very severe. If this is the case, then limiting the amount of milk that he drinks and replacing it with regular food will be very helpful. If this is not the case, then another cause needs to be determined for your son's anemia. It could be that he has a genetic disease, or potentially something wrong in his bone marrow such as leukemia. However, this would be the first thing that your doctors
would look for so I would imagine that you would have been told this by now. Regardless, your son needs to be seen and treated by a specialist. I would suggest that you schedule an appointment with a hematologist
for this problem. Simple blood test can determine the cause of his anemia and help select treatment options for him.