I’m terrified of dying, please help me.

I’m 20F. A few weeks ago, I experienced heart palpitations. My heart rate went up to 152 bpm. I immediately went to the ER. They did an ECG and found tachycardia, then gave me meds. After that, they repeated the ECG, and my heart rate had gone down. They also did blood tests, but nothing abnormal showed up. However, I couldn’t get over the experience because the palpitations happened out of nowhere. If I had drunk coffee or an energy drink, I wouldn’t have been so worried, since I’d know what caused it. But having it happen while I was just sitting made me really scared, and I couldn’t stop thinking, “What if it happens again?” I had never experienced anything like that before. Sure, I had minor palpitations before, but nothing that intense, so I was terrified.

Later, I went to a cardiologist. They did another ECG, and my heart rate was a bit fast again (probably because I was nervous), around 93 bpm. The doctor reviewed all my previous ECGs, did an echo, and said everything looked normal. He told me it was most likely related to panic attacks and anxiety, and prescribed a beta blocker just to help me feel calmer. After that appointment, I felt a bit better for a while, but soon I started having occasional pain in my left chest, sometimes spreading to my left arm. The pain would go away quickly and it was probably caused by gas, since I’ve been having digestive problems lately. Still, my brain refused to accept that explanation. I started touching my chest all the time, constantly checking my pulse. Whenever I feel even the slightest pain in my heart, I think I’m going to die.

I’m terrified, im always thinking about my heart, researching heart problems and diseases, wondering if I might have one. I feel like I’m losing my mind, and I’m afraid of suddenly dying because I know young people can die unexpectedly too. I don’t know what to do. My mental state is a mess. I’ve always had anxiety and health anxiety, but it’s never been this bad. How can I stop thinking this way?