I'm 24 years old, but have been experiencing heart palpitations for the past couple of weeks. Before it would just beat fast, but now it feels like it's pounding such that it shakes my body. I started feeling very faint a couple days ago, very lightheaded and a feeling like I wasn't there. This hasn't gone away and seems to be accompanied by a headache and extreme fatigue now. I don't know if it's related but I have been constipated for a week and have been experiencing bloating.