hi there, you haven't mentioned the age of your son, but it does appear to be related to his sinus drainage
. Small children are not able to usually cough
out the mucous stuck to their throat and it is via vomitting that the mucous comes out. Also you have mentioned tht he has a normal appetite and is playful so that is also assuring. He may be a little stressed out about meeting his bio-mother and good councelling and patient reassuring from your husban and you will help to alley some of his anxiety
. Now lots of love and reenforcing your care and concern for him will help him deal with the situation better. Take care.