well, the only experience was with a Gold Severum it was my gf's but we reckon it may have been bitten by the other Severum to get its swollen lip. I don't know if there's a disease for swollen lips, sorry
The most obvious reason for the lip problem is fighting. I'd give it a few days, if it doesn't clear up by then, you might want to try the emergency forum here for a quick answer. I know of no specific disease that would cause these symptoms.