Thanks for your responses, all.
The prednisone + verapamil combo did work for me. However, the side effects were too extreme and maybe not worth it. Now that my episodic cycle is about to end, I'll have more time to think through alternative solutions.
My "withdrawal" symptoms lasted for about 4 days, with the first 2 days being the most intense. My body ached, the hives were very angry, i could barely move from my bed, I had persistent nausea, shortness of breath, diarrhea, I constantly felt like I was going to pass out, I could barely eat, etc etc. It felt like what I'd imagine a drug withdrawal to feel like. By the 3rd day, I was finally able to get out of my bed and move over to the living room, where I lied down on my couch. I was also able to eat a bit, but not do much else. By the 4th day, I was feeling much stronger, but not 100%. By the 5th day, I had felt about 95% back to normal, however my hives were still there. Today is a full week after taking my last prednisone dose and I am happy to report that I'm back to 100% and the hives are finally gone.
All of the medical professionals I've seen kept telling me it wasn't the Prednisone, but I honestly can't think of what else it could have been. I was still on the verapamil when these symptoms started, so I feel it's less likely it was that.
Anyway, I hope no one else will experience these symptoms post-prednisone, but if they do, just know the symptoms last about 4 days (with the dosage and taper schedule I experienced) before any relief.