The teenager, whose precise age has not yet been ascertained, was picked up by officers on Wednesday night after drivers reported seeing a pedestrian on the central reservation near junction 7.
After he was found by police he was taken to emergency care for the night. It is believed he entered the UK illegally and the case has been handed over to the immigration authorities.
“He was split up from his parents a few days ago, and doesn't know which country they're in,” the Central Motorway Police Group said in a tweet.
"It's impossible to imagine how scared someone would be, not knowing where they are, not knowing where their parents are, unable to speak the language.”
He has been taken to a “place of safety” where he is now waiting for social services to come and take him into care.
A spokesman for West Midlands Police said the boy was believed to be around 15 years old. "It's understood the male - whose age has not been verified - is from Iraq and the matter has been passed to immigration."