Random misfire

Changed the coil packs and wires a few months ago. Within the last month and a half I had a problem with my engine "jumping". Since it has been progressively worse so I stopped driving it for a while. Last week I drove it to work just to see what was going on, it started misfiring so I stopped and got out and popped the hood. It was dark out that night, on coil pack one I could see a small arc jumping from the coil pack to the rail that holds the coil packs in place, also the plug wire was burnt on the side that connects to the coil pack, the spark plug side was clean though. Today I drove it to work because I planned on replacing the coil pack and the wires, which I did. That did not solve the problem now it seems worse. On a side note the coil pack I replaced was melted some, all the other coil packs seem fine I checked though and all the wires. From here I checked my plugs to make sure they were not over gaped, which they are not. I am worried I have caused a bigger issue by driving.