Hi. I am 27 year old and recently face this problem in two days (17-JUN-09). I usually carry a laptop bag which weights around 3Kgs in my shoulder bag and travel to office by bike. Recently i face a problem of chest pain in the middle of the heart that is left side., and feel indigestion the main thing is when walk for 10 minutes or climb a stairs., i feel like have shortness of breath and i start to breath via my mouth., i didnt had this problem in the past and can you suggest me what would be the cause for it.