I have had on and off pain in the lower left side of my jaw, anxiety, feeling spaced out, as well as left/right arm pain. could this be a heart issue?

Anxiety jaw/arm pain: At 21, it is very unlikely that this is your heart causing these symptoms, but it sounds like you should see a provider to talk through your symptoms and figure it out. If it is anxiety causing this, your doctor can help you start to control it, so it doesn't control you! Talk therapy may help a lot. Or medication. But first, make sure it isn't anything else. Breathe slowly. And good luck.