Okay so, I'm very skinny, I weigh about 6 and a half stone and I'm 15 - I know very underweight, every now and then I feel like my heart skips a beat? At least I feel like it is? Or like a weird beating pattern? Doesn't happen often but just a concern - also SOMETIMES when I'm lead down I can feel my heartbeat without putting my hand on my chest, I just feel it? I don't know what my resting heart rate is. I will also mention I'm kinda like a hypochondriac, I always think something is wrong with me.. :(