Asking for your thoughts...

Hi everyone! :)
For the past several weeks, David has had a really deep, nasty cough. We have tried several different things already, but nothing seems to help it go away. It bothers him, as it makes it difficult for him to sleep at nights, and is just a nuisance during the day. We think that perhaps it has something to do with the very dry weather right now and all the sand and dirt particles which are being blown around in the air. I think today, he's going to try and contact a doctor we know in Moscow. Sure would appreciate your thoughts for him... that this crazy cough would go away. Thanks!