Additionally....
You describe the chest pain as in your upper left chest; Your heart sits slightly to the left but behind your sternum and is the size of your clenched fist so not where you describe the pain.
I am in the Medical Profession and deal with patients with chest pain on a daily basis. I don't profess to being an expert in the cardiology field by any means, but what I do know is that the symptoms that you are describing do not sound 'cardiac' in nature.
The post above is correct. Heart attacks, Angina, the failing heart and other generalised heart problems do not usually manifest themselves as sharp pains. Normally they are dull, crushing in nature and nearly all of the time, are accompanied by other symptoms such as Nausea, sweating, fainting, dizziness, vomitting, breathlesness etc.
Sharp chest pains can be a sign of a number of non-cardiac conditions ranging in severity. Luckily, most are not serious in the great scheme of things. Some examples are pulled intercostal muscles (have you done anything strenuous recently?), Shingles (Do you have a funny rash following the line of a rib? Shingles affects nerves which could explain the 'ant' symptoms).
Of course chest pain is a great cause of anxiety to people and this anxiety often enhances the perception that people have of the pain. If you are subconsciously expecting it, you will feel it, whether there is actually something there causing it or not!
Athough frightening, remember that pain in the chest is not necessarily from the heart. If it is, you'll know something is seriously wrong! There are so many organs and tissues in the chest area; Skeletal muscle, intercostal muscle, nerves, the skin itself, glandular tissue, lungs, pleural cavity, bone..... the list could go on. These are all moving parts and the chest usually expands and relaxes 12-16 times a minute so at some point some bits will get sore.
I hope this puts your mind at rest regarding the cause of your pain but of course, getting a propper check up is always advised if you are still concerned.
Joel,
I'm almost certain that heart pains are seldom if ever "sharp". It's my understanding that heart pain is almost usually a deep, dull aching pain, and an intense gripping pain in a heart attack. Any sharp, stinging, or sticking pains are probably in the ribs, muscles, or nerves. I tell you that reluctantly because there are always exceptions. If there are no other symptoms, it's probably harmless. If it's almost time for a checkup anyway, you may want to mention it to your doctor just to ease your mine (and mine!).