I've mentioned this before (but not on this forum).
A friend and I BOTH have a neurological reaction to Zyrtec: numbness, sometimes in the side of the face, temporary blindness in one eye, numbness in the fingers, and possibly in one arm near the hand. It's something they don't talk about, but it happens. If you were taking Zyrtec at the time you had these issues, maybe it's to blame. (I'm not even sure that many doctors know about this).
I had a TIA in 2013 - it may have been more of a stroke than an actual TIA because defects DO show up on an MRI - this is because I trusted my meter - it said 2.6 - a blood test in the hospital said 1.7. The FDA later ordered that this meter be removed. It's no longer available.
I had what might actually be a TIA last year - numbness in my mouth, the left cheek, the left side of my mouth, and, IIRC, a bit of numbness in my lower left leg. It all resolved completely in a few days. My INR was fine. I don't know what caused it. But, as I said, it all resolved.
I haven't had AFIB, but I DID have aortic fibrillation (my cardiologist didn't refer to it as AFIB). My heart rate quickly jumped to 130 and higher upon ANY exertion. I had this for a few days before my electocardiologist defibrillated me in his office. The episode didn't return. I had an ablation that destroyed the node that was responsible for the aortic fibrillation. I'm now pacemaker dependent - but, aside from rhythm problems that were probably there (and will probably always be there), things might be more or less okay. I have to work on endurance, but I may be about the same I was at my last appointment with the cardiologist.
As for my Aortic fibrillation - I felt it right after starting any activity - even walking a short distance. I wear an Apple watch, so I can easily get my heart rate. I don't think I've had other fibrillations (though I DID have tachycardia a few times in the past - no fun and kind of scary. They resolved a few times, but required a jumpstart (atropine, delivered in an ER), a few years ago.
I hope your issues quickly resolve and don't return. And, if you take Zyrtec, consider that this may be a cause of your neurological issues.