My son who is 14 has been nauseous for 4 months and I m wondering if it could be related to his Invisalign? He has hasmd tins of lab work, seen a GI doc and a cardiologist. Now he us being told it s anxiety. He was a completely normal child up until 4 months ago; social, good appetite, outgoing, type B personality.
Did your son have a recent growth spurt?  There is a common phenomenon that can occur in growing teens called physiologic postural orthostatic tachycardia.  It results when the autonomic nervous system is out of sync with the growing child.  You would determine this at the bedside by measuring his heart rate after he is lying down for 20 minutes and the right after he stands up for a few minutes.  A difference if greater than 30 beats per minute is suggestive, and it should respond to increasing his salt and water intake. Find out soon because the sooner this is identified the more quickly it can be relieved. It does not sound like anxiety and I do not think the invitation is causing any problems.