headache nausea hard time breathing sweat cold body

Hello, yesterday at night while sleeping i woke up to something like an inner sting under my left arm and was having hard time breathing from it so i sat up and while sitting all of a sudden i felt everything going heavy on me and could not breath well, then my hands and feet became somewhat numb, for around a minute i was feeling cold and sweating at the same time and had a feeling like something was burning inside my chest, i went to the ER (my parents drove me there) the doctor after doing some tests like checking my blood pressure and hearing my heart beat and how im breathing told me that i am over exhausted and need to rest for 5 days at home and prescribed magnesium pills for me to take one each morning, i admit that i have been working a lot and drinking lots of coffee but i feel that this is not the case.
Things started 3 days ago when i felt a headache from one side only (left side) and went to a nearby clinic, the doctor prescribed "Airtal" and "doxepin HCI" the latter made me sleepy and its prescription said for people who are tired etc... so after asking the doctor he said i can stop it and that was last night when all this happened.