Hello ! Even if you are too young to have any heart problem per se, it is always better to get it excluded by getting consultation done with a cardiologist. Once it is excluded, you may be having allergic bronchitis along with co existent common cold due to which you are feeling shortness in your breath. Pain in back and upper abdomen could be due to hyper acidity or co existent galll stone, or pancreatitis. Consult your physician if not relieved,

Hello dear hope you be fine dear lets discus your issues ine by one
Pain in upper abdomen left side chest and arm,,dear mostly these symptoms are because of myocardial infarction ,myocarditis aur acidity,,,for myocardial infarction your age is too smal ,,,for acudity notice if it occur with food or not,,,
Then you had cold two reasons it is either common cold or sone tomes in infective endocarditis condition is like same
Dear you re young female in fertile age you might have anemia which also cause theses symptoms ,,,,,,,get you full blood counts dobe and ecg it wil help you in diagnose
Stay blessed