Possible Atonic Seizures?

I'm in my mid-50s and have always been exceptionally healthy. I began getting lightheaded when I walked and talked in late July, and was diagnosed with Long QT Syndrome in early August. I was referred to a cardiologist because of the LQTS. I attributed my increasing lightheadedness to the beta blocker I was subsequently put on, but my PCP and cardiologist both assure me that my meds are not the cause. I underwent an echo-stress test and basically fainted after 5 minutes on the treadmill; I was perfectly fine until I started responding to the tech's questions. (I say "basically" fainted because I remained semi-conscious as I dropped to the ground). My cardiologist eventually ruled out my heart as the cause of my lightheadedness and referred me to a neurologist. I had an MRI and blood work, but--for some reason--no EEG. The neurologist, too, ruled out the meds I was taking as well as diabetes for my lightheadedness. My cardiologist referred me to a second neurologist, but their first available appointment isn't until late March. In the meantime, my lightheadedness has progressed to the point where I'm unable to walk at more than a snail's pace--and even then with some difficulty--without at least feeling like I'm going to go down. My subsequent research has me wondering if I may not be having seizures. I realize now that I may have been having atypical absence seizures for as long as I can remember (remaining conscious and somewhat aware of whatever is happening around me, but unable to shift my gaze or talk for up to a minute, with full recovery taking several minutes), but have had them in conjunction with what I thought were heart palpitations so I always attributed my symptoms to (misdiagnosed) mitral valve prolapse. And now I believe that, in addition to atypical absence seizures, I may also be having a type of atonic seizure: pressure on the top of my head and shoulders; aura in my peripheral vision; unable to speak, shift my gaze, or move my body; feel like I'm going to black out; legs want to buckle; chin, cheeks, and wrists go cold; eyes blink as I struggle to remain conscious; and gaze sometimes fixes on the ceiling. I somewhat understand what's happening around me during these episodes, which can last for several minutes, but am unable to respond to questions. I feel weak afterward, and it can take several minutes before I can move or feel mentally strong enough to respond to questions. This sudden lightheadedness has quickly and drastically changed my life. I can barely walk from room to room in my own home without experiencing these episodes. I'm in a desperate holding pattern until at least late March, but wonder if anyone else has experienced similar symptoms and whether they've been diagnosed. I'm doing as much research as I can because my doctors are at a loss and it's now up to me to come up with suggested diagnoses for them to pursue. Do these symptoms sound familiar to anyone?