lately I have experiencing an irregular heartbeat. it sometimes beats 2, stops, beat 3, stop, beat 20, stop etc. along with this has been a headache, dizziness, a weird sensation in my head, I can hear the beat in my head. it's like a spidery sound and feeling. it's like a cap of veins streaking across my the top of my head. should I be worried about this? there are times when the heart beats so hard and so fast. I sometimes think it is coming right of my cheat. I try to correct this by holding my breath and bearing down. slowing the rate down. I am taking synthroid and elevil for sleeping.