My heart's been racing nonstop for months. Is there anything I can do to calm it down?

Heart racing. For starters your doctor can run an ekg (make a tracing of your heart rate and regularity). He can then send you to a heart specialist if needed who direct the treatment for fast heart rates when needed.
Needs exam plus EKG. A person's heart rate speeds up and slows down (within a normal range for the person's age0 throughout the day, depending on his activities and emotions. If a person feels he has a sustained rapid heart rate all day long, even when resting, then something is wrong. A doctor can examine him, check his ekg, and start treatment as needed. Several medical conditions cause rapid heart rates.