A curious question... (chest pain related)

For the past three years, I've been having recurring chest pain, mainly in my left chest area (mainly the lower inner part amd outer part next to the shoulder), sometimes on my left arm area, rarely on my right area, and hardly on my back area. However, like a week or so after I took the TMC and went back to my normal eating habits, the chest pain had gotton worst during the, especially hours after I do pushups. However, I had noticed that the pain gets better as I put heat on the area. It eventually got back to its usual annoyingnace when I stopped doing pushups.

A few weeks after that, I had some pretty bad chest pain (but no erectile problems) one day that also went to the right side of my chest and this had me real worried. This got me into a habit of putting my hand over my heart area to see if the pulse is fine, which it is. However, I had noticed that if I jog a short distance (I recently took up walking and jogging. The distance is like between 40-100 yards. I also jog a little slower than others but do it instantly upon walking instead of speeding up a little.) I often get out of breath quickly (my heart beats rapidly.), and if I just walk but come upon a slight hill, I find myself needing to take a small breath of air (in other words voluntarily breathe instead of involuntarily breathe). Also, when I climbed up a ladder yesterday, I found my heart rate to be a little fast. Finally, in a cession of 20 jumping jacks (which was after the walking/jogging), I found my heart beat raised a little.

Now before you think I might have cardiovascular problems, let me say this. I often lay down sideways on my computer chair (and look to the left at the computer screen) for hours at hand, and this bad posture might have strained my chest and arm muscles, especially my left ones. I'm thinking this because the left side of my neck sometimes hurts as well.

Just to let you know. I'm 6 feet tall, weigh 148 pounds (The most I've weighed in my life would be near 160), is 21 years old, didn't excercise that much (includes cardiovascular exercise), but does engage in walking from time to time. I'm quite skinny looking and doesn't look fat at all. Also, I didn't encounter any shortness of breath during those chest pains (just a lot of stress) and no erectile problems afterwards.

Now here's the question. Did I have a heart attack on the weeks the chest pain got bad and that I may be suffering from heart faiilure or that the pain is simply muscle strain and that the shortness of breath I get from jogging is simply from not excerising that much? What do you think is the case?