Sudden onset of insomnia ALL WEEK

Hello all,
Hoping someone can help or at least relate. I have always been a good sleeper and never had a problem getting or staying asleep. I generally sleep like a log. All that changed this week. Monday night, I had a panic attack that I think was triggered by my tight chest because of GERD symptoms - and I had some scary thoughts about the breathing, which then activated my fight or flight response. I couldn't fall asleep, no matter what I tried. Finally, at 2am I took a Lorazepam - I had a bottle from an ER visit a few months ago that I saved for an emergency. Mind you, I didn't even want those pills from the ER, and I only took 2 after the initial emergency (heart scare). Anyway, the cycle has repeated all week. Every night I try everything and then give in and take an Lorazepam (1mg).Well, I did this Mon through Thursday. I teach college for my job and I was panicked about going on no sleep. I really only got between 3-6 hours each night (the 6 was only one). Last night I did NOT take a Lorazepam. I tried melatonin instead.. did nothing. I have seen my Dr 3x this week! The first time was a regular visit on Monday, then I went back on Wednesday after the panic attack to go back on my beta blocker that I went off in June because I felt like my heart rate has been up all week. Then I finally went to the ER thursday because I was worried about my heart. They did their usual screenings and said I was okay, and told me to see my doctor. My doctor is putting me back on sertraline (i had been on it before) 50mg daily, just started today. I am totally okay with the sertraline and hopefully it will make a big difference with my thoughts that I have that trigger panic attacks. But I am so worried about this sleep issue. I literally slept 0 hours last night! I was in a "meditative" state sometimes, and laid down with my eyes closed relaxing, but I did not sleep. I am so scared to keep taking the Lorazepam, my doctor said it is okay and safe as a last resort but I am trying not to do it every day. But I seriously cannot sleep otherwise. Is there a chance it would be okay to use it until the sertraline kicks in more, and I could go off it? I'm currently taking 25mg metoprolol (beta blocker for heart palpitations) losartan 50mg (high blood pressure) and now sertraline 50mg. Also trying nexium for the terrible GERD situation. I know this must sound like I am a mess - and I feel like a mess. I used to be on no meds, running marathons and other endurance events, felt great and slept fine. The past year has been horrible for me and I am getting so depressed and desperate. I just want to be able to sleep so badly but I know the more pressure I put on that, the less likely it is to come.