Pain on the left side of my Chest

Okay.. So i am 21 years old. Spent about two years being lazy, eating bad foods, candy and not enough kcal..

A couple months ago i got into this new lifestyle.. And when i started jogging i started getting pains in the Left side of my chest. ITs not intense paine like if i fell or hurt myself.. Or if i got a wound or something.. Its more like a stining pain.

On the right side of my chest. To the left on the side of the right nipple. I feels like it could be the heartl.. It really scares me.

It dosent come always.. Yesterday i did a jog for 15 minutes some short uphills/Downhills.. No chest pain.. But a couple times earlier i got the pain.

Also when i had short time to get to the buss the other day.. I got this pain when i started running to reach the buss..


Also i got a slight stining feeling when i walked up a "Sharp" Hill thats quite hard.. I walked really fast as i usually do.. But this time i got this slight stinging.. Not as hard of a stinging as when i got it running to the buss or jogging.


I find this kind of pain weird.. Because i NEVER get this when i am in the gym jogging at 13.0 and 4.0% Incline.. Or when i am lifting weights to the point of fatigue..


I got a doctors appointment tomorrow but really want to go to the gym today.


Anyone experienced this?? should i be worried???