I think you are overexerting yourself during workout. As you said your EKG report is absolutely normal, so nothing is wrong with your heart but it is a spasm in chest muscle which gets aggravated after touching or giving pressure. Apply some muscle relaxant or anti inflammatory ointment like Volini gel over the affected area.
grendslori provides an good insight as well.
Here's a link that can provide more information as well: Most of us on this forum can identify with your problem, and it can be frustrating at times.
http://www.medhelp.org/posts/Heart-Disease/Sharp-Pain-on-left-side-of-chest/show/250025
Heart related chest pain is never a sharp type of pain as you describe in your post. It is usually a dull, crushing type of pain. Also, someone in your age bracket rarely has true heart related chest pains; those that do, have some form of serious congenital heart disease, which would have been picked on you long before now. Chest pain is related to a lack of bloodflow to the heart muscle which is caused by coronary disease or a cardiomyopathy. Coronary spasms can usually be picked up on a stress test; I myself have this problem. Also, many people who have spasms with the coronary arteries also have other spasm problems with the body such as Raynaurds or esophagel spasms when they try and eat. Try some anti inflammatory drugs and see if that helps; give it a couple of days and then see your GP if you have no improvement after that.
Angina variant will provide links. If you have any followup questions feel free to ask. Good luck.
Is that a serious and dangerous condition? i tried looking up coronary vessel spasms but nothing comes up except coronary artery disease, which i really hope isn't the case especially since I'm 22 years old.
You may want to look up costochondritis because your description of sensitivity to touch and hurting when you breathe in could be describing this sometimes extremely painful problem. Did none of the doctors suggest this and prescribe cyclic anti-inflammatory medication for a few days and resting the area until it feels better? I'd ask one of those docs you already saw about this if they didn't.
You may have strained a muscle. If it were related to a heart problem, there wouldn't be any sensiivity to touch. With that aside, it is possible the pain is related to coronary vessel spasms. An EKG would not recognize that condition unless there is a spasm or a rhythm at the time of the test.