Kristin is right!
This has to be dealt with right away. One thing you don’t need on top of GBS is some sort of infection that entails anti-biotics that could complicate things more.
Do see about training/trainers or find an alternate way of eating and dealing with this issue. Gotta ask tho, has this been building up or something? Or was it a sudden surprise – events preceding a sudden event [strange visitors or the like] could be triggers to a dog for what can only be a dog’s reasons.
You want this dog to be your comfort, but if he gets worse, he becomes a threat and that’s not good. Training and help can hopefully avoid that.
Good luck and keep heart!