DS3 (3) has for over a week been taking a sharp in take of breath and then coughing. When I ask him if he's OK he says "yes, I've just swallowed a spanner". Now he is perfectly fine apart from this sharp intake followed by a cough. I questioned him further and he is adamant that he's swallowed a tiny toy plastic spanner out of his brothers lego set. 
My mum took him to the doctors for me today (DH working away and I don't finish till 8pm) and the told him the whole story. The Doc checked him over and said that he's had a viral infection which he is recovering from and there is nothing he could do now. When my mum questioned him over the spanner he just laughed and said he'll be fine - its been a viral infection! 
Am I right not to be happy with this answer? What should I do now? DS's fine but I'm still worried that the Doctors not taken the "I've swallowed a spanner" line seriously and because he doesn't know why he does the intake of breath he's just said its a viral infection?
Help!!