My left arm was heavy, and when i went to feel it, my left hand was cold. my right arm feels fine. could this be heart related?

Maybe (not) . . .: Go to ER now. Don't pass Go. But do call 911 to expedite your care. You didn't describe pain or weakness but I suspect latter w/"heavy". While not common in 20yo, sudden onset of weakness in any limb is suspicious for stroke. Think FAST (http://www.stroke.org/understand-stroke/recognizing-stroke/act-fast). Painful cold limb is suspicious for ischemia (inadequate blood flow). Either way, go now.