Chailem,
It depends greatly upon what caused the spontaneous pneumothorax. If you have underlying lung disease, that will have to be treated. If you smoke, stop. However, if you are a young adult, with primary spontaneous pneumothorax, will it happen again? You have a higher chance than the general population, but it is not a sure thing.
As you noted, in many spontaneous pneumothorases, the person does not have respiratory distress. But, that can change in an instance, especially at high altitude (air plane or mountains). If you develop a tension pneumothorax, that can be life threatening.
As to treatment in the field. If you don't have advanced medical training, do not try any invasive therapies. Don't go stabbing around the chest with a needle, you can hit tubular things that will bleed like stink. About the only thing you could do is get down out of altitude, stop any physical activity, try to calm down as much as possible (you've been there before), use oxygen if available, and get to medical care.
You can find some information about spontaneous pneumothorax here, that is much too long to include in this post -->http://en.wikipedia.org/wiki/Pneumothor
ax.
You really should speak with a pulmonologist before you go on your trip. If you go, check out where the major hospitals are, close to where you will be surfing.
Have fun in the sun.