He's not starving, and if he has RI he's probably not going to eat to be honest. I've never heard of using VIC's on a snake. I would say up the temp like you did and increase the humidity a little and if he doesn't show signs of improvement within a week or you start to see a mucus build up in his mouth its time to take him to a vet. Either way I would probably say going with a vet is the safest way to go