2005 Altima 3.5SE p0420 code, and now white smoke out of passenger side exhaust

Hi everyone, I was driving my car (83K miles) home during a snow storm and just before getting home I heard a clunk (Thinking I
had probably hit some high pile of snow on the unplowed road) and didn't think much of it until 5 minutes later I got the SES light but didn't notice any change in the running or idle of the engine. The next day I didn't run the car until I had to move it around my driveway to make space for guests and then came the smell of gasoline (Not rotten eggs) and white smoke from the passenger side of the dual exhaust. So at first I was thinking I might have knocked a seal loose, but now I'm worried it's something much much worse that coincidentally happened after the thunk.



The code I got from my reader:

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)





Here's some recent background of issues that may or may not have affected this situation.

1. Oil change a little over a week ago
2. Was experiencing burning up ignition coils and in turn spark plugs. Went to the shop 3 times until a mechanic that had seen the problem before realized it was a loose negative cable on the battery terminal that was arcing back into the system and frying the coils. By the end of August (This started at the beginning of July) I had new ground cables all around, new spark plugs, and new ignition cables and hadn't had a problem since.

Any help or advice on this would be greatly appreciated, thanks!