Panic attacks or something else?

I’ve been experiencing these strange episodes. They’ve happened before, as far back as my teenage years. The past month they’ve become much more frequent though. Sometimes I’ll have them twice a day, other times I’ll skip a few days and be fine.

The episodes can last a few minutes to 20 minutes although it seems like hours. I can always feel the buildup. I begin to feel light-headed, dizzy, nauseous, my heart jumps around, I have lots of butterflies in my stomach, throat tightens, and I have this awful feeling that I’m dying or having a heart attack. Sometimes I get hot flashes and feel like I’m on the verge of fainting. I lay down but that doesn’t seem to help. My blood pressure is on the lower side (100/72) but I’m not sure that’s low enough to cause issues and my doctor has never been concerned.

Awhile back I was given Clonazepam for anxiety but I only ever took them before bed to help me sleep. I don’t have any left so I’m not sure if taking it would help in the moment. From your experience, does this sound like a panic attack or something else? This is getting frustrating. I walk around in fear of another one happening and I’m wondering if maybe I’m even bringing them on at this point. It’s important to note I do have a doctor’s appointment Monday.