What Causes Rapid Heart Rate Along With Throbbing Pain In Shoulders?

Hi last night my heart was beating very fast and it lasted for about a hour, I had taken a zyrtek for my allergies but this is the first time this has ever happened. I would restless and could not go to sleep for a couple of hours. I have Fibromyagia and osteoarthritis I was just a little scared thinking it might be a stroke because I have been having this throbbing pain in my left shoulder.