Tough Question. As far as what to do with the kid its not an easy question. I suppose the idea is just to talk to him and see what he thinks about the whole situation. Let him know how involved you are willing to be and what you are willing to do for him and let him have a part of the deciscion. The fact that you are in Saudi Arabia does complicate matters somewhat. Does he even speak English? At least you never knew about before, so you aren’t really responsible for it. So why do you now find out about it, is my question. Did the mother decide to tell you after 15 years, or at least get out the word? Your life sounds pretty complicated so I won’t pretend to give any more advice than that. I am just trying to think from the kids point of view.
Paul, have the blood test done. If he’s yours, do what you would have done had you known about this kid from day one. There’s no way you can make up for lost time but you can establish a future 
And please keep in touch with us. If you abruptly stop posting, I know I’m going to fear that ran across your old friends with the long memories and thus never made it back out of Panama!
Me, keep in touch? I practically live here. Drop me a line whenever you like.
I have an e-mail out to the US Embassy in Panama City and am awaiting a reply. Once I have the name of an approved local doctor, I will make a quick and quiet trip down there. I hope to be out of town in two days.
I also need to keep my wife informed. She seems OK, but she could freak out at any point. You know how people are.