chronic throat clearing.

I co-parent an almost 5 year old boy. Within the last month he has been clearing his throat multiple times per minute. Approximately every 10-20 seconds. His mom is in the medical profession and I asked her to check out his throat incase there were something obstructing or otherwise causing irritation. She replied back that there was evidence of irritation but she concluded it was due to the throat clearing and not the actual cause. My boy says there is something in there, but he is across the board with what it is etc so not a credible source of information. His mother suggested trying Allegra for kids which I understand is an over the counter antihistamine. He is on his second dose and there has been no reduction in the throat clearing. My take on his condition is that it is a nervous habit he has picked up. I am reaching out to reddit parents asking if any of you have had a similar situation. If it is indeed a nervous habit how would one address this? Thank you for any help you can provide! via /r/Parenting http://ift.tt/2aE8TKz