The pain you're feeling in your left arm could be quite a number of things. Have you ever injured that arm or shoulder in any way? Do you do any sort of repetitive motion, either for work or relaxation? You didn't say anything about numbness, which I think rules out carpel tunnel, but I'm not a doctor, so I'm not sure if there is ALWAYS numbness. It could be a tendon..........if you play tennis or any sort of racket game, tendinitis is a common malady. You could have done something to a ligament in your hand which might radiate up your arm as well as into your fingers. You could have some rotator cuff problems in your shoulder. If you have very tense shoulders that could lead to these problems. If you sleep on your left side, that would just add to the problems in your left arm.
You're concerned because you're feeling a bit under the weather. Nausea, fatigue, aching and "a little chest pain which is sore to the touch."
I live in Washington state and our weather is very much like yours. Right now, thousands of people are getting hit with the first colds and bugs of the winter season. I'm guessing that's your problem as well. And for that chest pain that is sore to the touch? It's not related to your heart! Your heart is encased in a cage of bones, (ribs and breast bone) and those are protected by your chest wall. How do you know it's "sore to the touch?" Is it because you keep poking it to make sure it's still sore? LOL I'm not laughing AT you, I'm laughing WITH you. I used to do the same thing when I had really bad heart anxiety. I'd get a chest pain and spend days poking myself until I had a nice bruise which I could then run to the doctor with and say "see, it IS my heart..........not only is it sore, now it's leaking!" You should have seen me when I went through my brain tumor stage. Now THAT was amusing! (NOT)
You cannot touch your heart from outside your chest, so whatever your touching that is sore is most assuredly NOT your heart.
Take your age and your apparent excellent health into consideration as well. I work in a hospital and don't get 26 year olds having heart attacks. Keep up your good health habits and you won't have to worry about a heart attack for at keast 40+ years.................if ever.
I honestly do not think you have any heart problems. I do think you have health anxiety and the heart is the prime focus for most of us.
If you want to ease your mind about your heart, see your doctor, but while you're there, discuss getting into some therapy to help you deal with the health anxiety. There IS an underlying cause for your fear and once you figure out what that is, you can beat it. It could be something as simple as you being traumatized when your grandfather passed away. If you were young enough and close to him, that could easily have been the trigger for your anxiety. But you won't know for sure until you begin exploring.
Let me know how you're doing, OK?
You're going to be fine!
Peace
Greenlydia