He doesn't have any condition where he senses electromagnetic fields. It's a condition he made up entirely in response to how Jimmy violates Chuck's world view where Jimmy is inferior to Chuck. It started soon after Jimmy got a law degree, it got better when Jimmy worked under Chuck, because Chuck liked being his boss and controlling Jimmy's big case. It got worse when they had a falling out. It got way worse after Chicanery where Jimmy proved he can be a better lawyer.

If Chuck actually had an issue, how did he function as a successful lawyer for most of his life? When he had severe symptoms, it was all around his head, his ears rang, his eyes hurt, his head hurt, so how was a reflective liner in his jacket sufficient to protect him for a season or so? Why does he routinely only experience symptoms after being told about hidden electronics?