Did you have RF ablation, and if so, or even if it was PFA, did they do a TEE on you (Trans-esophageal echocardiogram....like a colonoscopy device, but it goes down your esophagus and the sensor tip sits near the heart where they are generating lesions to isolate the re-entrant or the pulmonary veins)? I had TEE both times because mine was RF, and they want to avoid burning the phrenic nerve and the esophagus like it's their own mom they have on the slab before them. My first ablation, the very worst thing, even worse than lying flat on my back for three hours, was the first hour after coming to. I couldn't swallow ( I forgot all about this when I replied to you earlier about what to expect...which is amazing that I could have overlooked that, or maybe I wanted to spare you that detail to avoid freaking you out!). My throat was parched, thick, stiff...it was a nightmare. For the second ablation, I mentioned this to the anaesthetist when he came to my cubicle prior to the operation, and he seemed genuinely happy that I mentioned it. He said he'd take care of it...and he did. I read somewhere that they spray a desiccant, or maybe coat the tip with one, and it keeps the area free of fluids. When they remove the wand, it might irritate the endothelial lining next to it. This is just a guess, but I thank the Great Lord he listened and took pains to ensure I didn't have a repeat.
All this story to say that I think this may be the issue for you. Or, you may just have a virus and it happens to have take root four days after exposure, maybe in the hospital itself? I think you should ask to speak with one of the nurses who works on the team, or on outreach if they have such a function after the ablation, and run it past them. Or your GP or cardiologist. It might benefit from some treatment instead of having to endure it, or to experience a continued deterioration.