hiccups are a spasm of your diaphragm, to get rid of them is the same as a normal spasm, exercising the full range of motion, so you breathe in as far as you can go, even through a hiccup if you have one, hold your breath, then exhale fully, then inhale again fully etc etc for bowt 5 mins or so...
i never get hiccups anymore, cos i do this from the 1st one...
as for the pain, its your muscles tightening, the fight or flight instinct pumps masses of addrenaline into your system (from your adrenal glands near your kidneys) which causes your muscles, esp in your chest, (running or fighting your gonnna need alot of air and blood pumping) to tense and get ready for action, when this action doesnt come, such as when you realise that there is no immediate danger, your muscles will take abit of time to come down off edge, esp since your usually sitting down using low o2 and activity after these computer generated frights....
mum always said i shoulda been a doctor...