My yellow tip sudden has a swollen mouth for the last 2 weeks. Still eats aggressively and nothing has really changed in the tank. Normal water changes, normal dosing. Nothing around or bothering him.
I had a Haddoni with swollen mouth like that. I did a bunch of water changes and he got better. I think it is water problem. Send your water to have check and see if there is anything out of wack. Mine was a long time ago before we have this service so I did not do it.