How have i lost 15 pounds over the past few months without trying? i'm now 120. bloodwork is fine, but heart rate is often elevated from sinus node.

Need to be checked: If you have other symptoms - fever, cough, blood in your bowel movements, night sweats, a painless lump under your skin - you need further evaluation. You mention blood work is fine: you need a chest x-ray and thyroid tests also at a minimum. Are you exposed to any industrial toxins, fumes, or waste? Something is causing your weight loss. A careful evaluation is necessary to find it.