Hello Rei and Welcome <3
If Singapore is your homeland, I can recommend you to try learning some coping skills meanwhile, then see a dr after you return.
As a person who lives abroad, I say by any chance if you get treated differently in another country (no offense, due to cultural and social reasons), then it might have a negative effect on your psychology and cause more anxiety + panic. If you are not returning back to your homeland soon, then go for it, ask for help in Japan. Drs in Japan are very caring and good in all fields as far as I know (heard from my many Japanese friends :) ).
In the anxiety forum main page, the first "Resources" topic has fantastic links. You can check those coping skills. During a panic attack breathing techniques play an important role.
Here is the link to topic: www.healingwell.com/community/default.aspx?f=9&m=104206
And here some breathing techniques : www.healthcentral.com/anxiety/c/73076/34334/breathing-lessons/www.ehow.com/video_4405003_breathing-exercises-panic-attacks.html
As far as I can see, you are already taking a big step at knowing your issue and ways of calming yourself.
And yes, unfortunately after effects can be quite distressing also.
Hang in there
Age is just numbers *cough*39*cough*
Panic disorder - Health anxiety
Learning to deal with catastrophizing, ongoing CBT