Tingly arm, gets worse when I smoke, heart pounds with sweating, left hand gets cold. Suggestions ?

Hello I went to the hospital yesterday and was discharged within a few hours.. iv had a dead tingly arm for a whole week.. and every time i smoke it gets worse..my heart area has also been hurting and my heart actually pounds and makes me sweat at times.. i keep gettting achhey neck and shoulder and my left hand goes colder than the other(this is all on the left side of my body by the way).. the paramedic when taking me to hospital gave me a ecg and said that it looked like my main heart valve was bigger but when i got to hospital i had ecg and chest xray and things looked fine apart from the fact im getting over a chest infection wich antibiotics was not ggiven to me for..they discharged me and told me to go to doctors if it still happens in a few days...but thing is iv been going to sleep with pain and feeling and waking up and having it all day..whats wrtong with me im only 20.. iv also had head aches in my left temple and when i get stressed it happens then too..? Help im so scared..iv been under so much stress