*Caveat* - I am not a doctor (you should check with your own)! And this is not personal advice!
I have a very good friend who has had two pneumothoraces - one in each lung (you should see the impressive scars!) - and he continues to travel extensively. One of them happened on a film shoot whilst in Ecuador and he ended up in the local hospital for some time before returning to the UK. about 7 years ago
I'm no doctor either, but let me refer you to a couple of articles I found.
One which suggests that it is safe to fly 14 days after a pneumothorax (as long as it hasn't recurred): http://www.ncbi.nlm.nih.gov/pubmed/10597066
But it could be that some airlines require you to wait until 6 weeks after the illness, plus you'll need to submit a medical report: http://thorax.bmj.com/content/58/suppl_2/ii39.full
Check the fine print of your airline ticket, it may have those conditions imposed (if you fall ill on a flight and you haven't met their criteria, you may end up paying for the cost of diverting the entire flight!)
I think it best if you make a full disclosure to tour operators, airlines and of course your travel insurer. They may be able to give you clear advice.
Phil at the safety hub. about 7 years ago