Last night while relaxing before bed, I was watching cat videos on YouTube, when it felt like my heart stopped, built up pressure, then exploded and started beating again. Caused moderate discomfort and felt really anxious for no more than 10 seconds afterward. Then I was really tired, felt weak and lightheaded. Today, 12 hours later, it feels like my heart is bruised. Anything strenuous causes pain in my chest. The pain is in the same spot that I felt the "explosion" last night. And if I take a deep breath, it still hurts. So I have to take short, shallow breaths. Is it something for me to be concerned about?